conventional computing environments require manual reprovisioning , which is typically in response to an explicit complaint or negative occurrence on behalf of the acting user . even more elusive are overprovisioned users , as overprovisioning rarely generates negative feedback , however is typically indicative of underutilized computing resources . configurations herein coalesce provisioning with individual user demands to avoid underprovisioning and overprovisioning ( misprovisioning ). provisioning reassessment is performed periodically , such as on logout of a user , or in response to detrimental events ( typically an indicator of underprovisioning ). the disclosed virtual computing environment differs from conventional centralized server arrangements because conventional centralized computing environments do not coalesce cost and user demand to determine an appropriate provisioning level , or maintain a correlation of user activity to misprovisioning events , and do not automatically assess and reassign user provisioning as a result of a misprovisioning determination . in contrast , configurations herein compute a provisioning class based on expected usage demands weighed with the cost of provisioning a user in a particular class , and continually monitor and reevaluate the class to assure an appropriate provisioning level for the user . conventional arrangements require manual reconfiguration , typically through burdensome manipulation of configuration files , and reprovisioning generally only occurs after interaction with a system manager or operation staff member . further , many operations staff personnel may be predisposed to either underprovisioning or overprovisioning , since overprovisioning generally reduces successive complaints , while underprovisioning tends to keep information services costs lower . varying management goals and principles may drive this result . provisioning modifications are performed in response to an indication of misprovisioning to realign the user with a cost appropriate provisioning level . for example , a user initially receives a provisioned environment with 1 cpu w 512 meg . the user invokes a large drafting program , and the xp operating system ( os ) will help with large swap file . however , the user then experiences on the order of 1000 - 1 performance degradation from page faults ( thrashing ), a trigger indicative of underprovisioning . if the user had a half gb more memory , the page swapping would be substantially reduced . a best - fit rule indicates that is a threshold number of page faults occurs , memory should be increased from 512 mb to 1024 mb , thus adjusting the user provisioning to suit demands . fig1 is a context diagram of an exemplary virtual computing environment 100 employing a network of virtual computing services deployments 112 - 1 . . . 112 - 3 ( 112 generally ) for use with the present invention . each of the deployments 112 is operable to support a provisioned environment 122 on a user device 120 via a corresponding instantiation of a virtual computing environment ( 145 fig3 , discussed further below ) on a corresponding deployment 112 . each of the deployments 112 may be a virtual computing services rack , or cluster , as disclosed in the copending application cited above , or may be another computing resource , such as a specialized grid processing device , discussed below . a provisioner 134 , which may execute on one of the deployments 112 , receives an environment 142 including a parameter set based on each user &# 39 ; s profile and a desktop 162 from a profile repository 140 , coupled via a network 500 which also couples the deployments 112 as a grid of computing resources . the environment 142 is stored in an environment repository 141 including usage history , and the desktop 162 is stored in a desktop repository 164 , also specific to each user . the environment 142 and desktop 162 are independent , to avoid constraining users with similar desktops ( i . e . same department ) with similar provisioning a policy repository 180 also defines rules 188 employed by best - fit logic 136 in the provisioner 134 for selecting the provisioned environment 132 applicable to a given user 120 . best fit logic 136 , discussed further below , computes a provisioning instance 132 corresponding to a computing class 144 ( fig3 ) most appropriate to the user 120 , for execution as a computing environment 145 on one of the deployments 112 and coupled to a corresponding provisioned environment 122 at the user device 120 , typically a thin client operating the gui 121 . the appropriate computing environment 145 includes , but is not limited to , selection of a virtual computing services deployment 112 , typically a cluster proximate to the user 120 , a general class 144 of computing services ( terminal service , hypervisor or grid , discussed further below ), and within the class , user parameters . the provisioning environment 100 is periodically reevaluated based on triggering events to reprovision the user as necessary to maintain the best - fit matching . example rules applied by the best - fit logic 136 , and the policy considerations underlying them , may include , for example : if user has & gt ; x page faults in y hours , then allocate 512 m more memory if user has less than 5 % cpu utilization over y days , then reduce cpu speed 50 % if user has hit & gt ; 90 % cpu utilization for at least a minute ( i . e . affecting other users ) then move from ts class to hypervisor class if user has hit & gt ; 90 % cpu for 20 % of the time , then invoke grid service these rules are exemplary ; other rules having different parameters and thresholds will be applicable to different scenarios depending on the management philosophy behind the policy . the provisioned environment 122 enabled on the user device 120 appears as a standard personal computer desktop , only without the physical pc present and via a thin client network box instead . however , the applications and cpu computations are performed at the computing environment 145 , operating as a virtual workstation inside the deployment 112 . the display rendering is then transmitted over the network to the thin client device as an environment instance 132 , appearing as the provisioned environment 122 . this significantly reduces the network traffic over the wan or lan , and consolidates network communication across tiers in to the data center housing the selected virtual services deployment supporting the users &# 39 ; s provisioned environment 122 with computing environments 145 ( fig3 below ) running on a respective deployment 112 . any number of third - party thin client devices are employable for use as a user device 120 responsive to the provisioned environment 120 , including wyse terminals , pda devices , and even pc &# 39 ; s themselves . the thin client devices 120 initiate a connection to the deployment 112 via a remote desktop connection ( rdc ) client application , as is known in the art , or other suitable connection medium , to the deployment 110 via a url or other mechanism , generally by a public access network such as the internet . alternate continuations may include an enterprise or corporate lan , wan , vpn , wifi , or other specialized network as circumstances dictate . in the example arrangement , the service is registered in uddi and the service that implements that uri receives the initial request . it then hands off to a connection broker component ( 124 , fig3 ) that is responsible for either locating and / or starting the environment and returning the address for subsequent exchanges supporting the provisioned environment 122 . the virtual services deployment 112 , in one sense , operates similarly to the national power grid . the various services deployments 112 - n are disposed in various locations in the network 500 based on the notion of making computation available in the network . this represents an interconnection of resources akin to the north american electrical power grid . conceptually , the architecture consists of a global catalog and a set of sites where computation is produced . rather than batch - oriented , these computations are demand - driven in support of interactive end - users via thin client devices 120 . this means specifically that demand is somewhat unpredictable , i . e . it can be characterized as being stochastic . the analogy to the power grid is particularly applicable because it represents a geographically disperse set of unpredictable resource consumers that each require a concurrent minimum level of service . the power grid within the us / north america thus may serve as a demand model for the environment 100 . for example , ercot is one of several , regional “ independent system operators ( iso )” in the north america system . these manage the scheduling of power on the electric grid in their respective region . within its region , ercot &# 39 ; s mission is to direct and ensure reliable and cost - effective operation of the electric grid and to enable fair and efficient market - driven solutions to meet customers electric service needs . of course , power distribution provided by the north american power grid is distinctly different from the virtual computing resources disclosed herein as the power grid distributes raw electrical energy in an analog form with no control over this analog signal after generating the sinusoidal impulse at a predetermined rate ( 60 hz ). there is , of course , uncertainty inherent in any shared , distributed system that supports a diverse set of workloads . a viable operation should be resilient in the face of failure as well as deal with unexpected and time - varying demand . ultimately , the physical infrastructure provided by the set of deployments 112 - 1 . . . 112 - n may be viewed as manufacturing plant that is shared amongst several workloads , each gaining access to sufficient capacity to meet their respective demand forecasts and the supporting scheduled delivery of plant capacity . in configurations herein , capacity is repurposed as demand varies . the implication of this dynamic repurposing of physical computers is that ( a ) there is some form of scheduling and ( b ) all of the prerequisite inputs are available in advance of a particular schedule being enacted . a particular “ service ” hosted in on the virtual services environment 100 is primarily a set of policies ( i . e . service level agreements ) governing how a specialized set of computations , collectively referred to as a 3 service , 2 will be delivered to a target constituency or “ market .” using the provisioned environment 120 as an example service , there are two tasks that must be addressed : demand forecast and capacity scheduling . this service is concerned with providing a user access to a desktop session via the network . the end user &# 39 ; s request for a desktop instance 132 is brokered via a mediation layer referred to as the connection broker 124 ( fig3 ). this is a core service that can be thought of as an application - oriented , ip load balancer . in the desktop 164 example , the connection broker 124 first determines the requesting user &# 39 ; s identity and class of desktop specified in their subscription . once this is determined , the second step in this process is to find a properly configured desktop 164 system sitting in inventory . if successful the system is assigned to the user for the duration of their session and specialized / personalized for their specific use . finally , the connection broker 124 returns instructions to the requesting user 120 on how to connect to their desktop . the physical deployment topology is designed to minimize latency and maximize fault tolerance and disaster recovery capabilities . similar to an akamai - like edge network , the disclosed environment 100 relies on a set of distributed locations where the deployments 112 , typically implemented as equipment racks , stand ready to become the primary service provider for an end user 120 . the racks are stateless wholly integrated clusters ( e . g . deployments 112 ) that can automatically provision desktops and requested applications from bare - metal at a moment &# 39 ; s notice , assembling personalized functionality on the basis of security policies and individual preferences associated with an end user &# 39 ; s identity . for example , if a call center employee is relocated from the new jersey office to an office in tokyo , the precise configuration and capabilities are instantly available upon login at the new location , with no loss of quality or performance . similarly , if a developer is working on a certain program on a set of procured servers in one location , he can log - in anywhere in the world and continue his work with no apparent differences . while each location around the world in the distributed network has self - contained storage , the data is regularly backed up to the master data center , providing robust archiving and data integrity and an usually efficient “ roll - back ” mechanism to previous - state configurations . fig2 is a flowchart of provisioning in the computing environment of fig1 . referring to fig1 and 2 , the virtual computing environment 100 provides , at step 200 , a method of managing computing infrastructure costs by defining a set of computing classes 144 , such that each computing class is associated with a per user cost , and accumulating a usage history corresponding to each user 120 in a set of users 120 - n , in which the usage history defines a user profile 142 indicative of computing demands of each user 120 , as disclosed at step 201 . the environment 100 regularly analyzes the computing demands to define and / or refine the user profile 142 for each user 120 , in which the computing demands are indicative of a provisioning cost of the user 120 , as depicted at step 202 . a virtual computing services deployment 112 ( deployment ), typically a cluster of computing servers and peripherals at various deployment locations in the environment 100 , provisions each user in a particular computing class 144 based on the user profile 142 , the per user cost and the provisioning cost of the class 144 , as shown at step 203 . ongoing best - fit provisioning occurs by periodically reanalyzing the computing demands to selectively reprovision the user , as depicted at step 204 . fig3 is a block diagram of virtual computing provisioning in the environment of fig1 . referring to fig1 and 3 , each of the virtual computing services deployments 112 is operable to provision one or more of the service classes 152 , 154 , 156 ( 144 , collectively ) as shown in fig3 , and is operable to provision a user 120 on any of the other deployments 112 - n via the network 500 . the connection broker 124 receives an indication of the instance server 130 selected by the provisioner 134 using the best fit logic 136 , and informs the selected instance server 130 to instantiate a computing environment 145 supporting a provisioned environment 122 at the corresponding user device 120 . often this may be the most local instance server , however network location is only one of many factors weighed by the best fit logic 136 . the virtual computing services deployment 112 takes the form of one or more virtual computing services racks 110 , equipped and implemented as follows . the instance server 130 further includes an instance manager 150 for maintaining computing environments 152 , 154 and 156 ( collectively shown as 145 ) for each class 144 . the computing environments 152 , 154 and 156 support the provisioned environments 122 by defining the respective memory , cpu and i / o operations in each environment 122 . the user device 120 is typically a low cost telecommunication device having sufficient capabilities to exchange keystrokes and mouse operations , as well as a display screen , but typically retains no nonvolatile storage ( i . e . disk drives ) and operates as a rendering device for the provisioned environment 122 for the user with respect to the computing environments 152 , 154 and 156 at the instance server 130 . upon provisioning , which occurs at initial login as well as according to predetermined intervals as defined herein , the provisioner 134 employs a user profile 142 from a profile repository 140 to assign a provisioning class ( class ) 144 to the user device 120 , and also assigns a separate desktop 162 from a desktop repository . the class 144 indicates the level of computing resources provided to the user 120 by the instance server 130 via the environment instance 132 , which in the example configuration corresponds to a terminal server 152 class , a hypervisor class 154 , and a grid class 156 , discussed in further detail below . a connection broker 124 establishes communication between the instance server 130 and the provisioned environment 122 via the environment instance 132 . the provisioner 134 employs the best - fit logic 136 including a history of previous computing activity in the profile database 140 by the user 120 in the profile database 140 to determine the class 144 . the profile includes , for each user 120 , an entry 142 having the identity of the user , and environment parameters applicable to the user 120 , including memory allocation , cpu speed , and i / o ( disk ) capacity . these parameters represent the current provisioning of the level and are recomputed and / or verified by the best fit logic 136 at each provisioning evaluation to maintain the user at an appropriate provisioning level . the instance server 130 instantiates a portion of available resources as an environment instance 132 for each provisioned environment 122 deployed on a user device 120 . each environment instance 132 is based on a particular class 144 , and corresponds to a computing environment 145 . in the example configuration , the classes 140 include a terminal server ( ts ) class 152 , intended for low usage demand users , and supporting a plurality of users in a common memory with a shared operating system . a hypervisor class 154 provides os and memory isolation for users with more specific usage demands , generally greater than the ts class 152 , and preallocates a portion of available memory and cpu resources for exclusive use for a user 120 . extreme usage demands invoke the grid class 156 , which delegates computing to an external computing grid 158 where computing “ horsepower ” is provided on a fee - for - services basis , particularly for short term intense needs . the grid 158 operates as another deployment 112 accessible via the network 500 , and may be a more robustly equipped cluster providing multiple service classes 144 , or may be a highly specialized computing engine reserved for high performance ( typically with commensurate cost ) computing . the instance manager 150 also retrieves a desktop 162 from an environment repository 141 , which may be the same as the profile db 140 or a distinct physical repository . the environment repository stores desktops 164 for each user 120 including the application suite 166 and operating system 168 for each user . the desktop 164 is independent from the provisioning class 144 , thus allowing users from the same group ( i . e . serving a particular business function such as legal , accounting , hr , etc .) to have common application arrangements without necessarily being bound to similar provisioning classes 144 . such an arrangement also avoids the need to place similar users ( i . e . from the same group ) in the same provisioning “ bucket ”, for example having highly mathematical intensive applications of the accounting group served by the same terminal services instance 152 . the application virtualization engine 170 operates in conjunction with the desktop 164 to provide each user with needed applications . as shown by dotted line 172 , the application virtualization engine 170 retrieves applications from an application repository 174 for invocation by the computing environments 145 . the application virtualization engine 170 makes desktop 166 enabled applications available , and also coordinates user / license provisions to maintain appropriate application / user invocation . an instance storage volume 180 provides mass storage services to each of the environment instances 132 , in effect acting as the local disk drive for each user device 120 . the instance storage provides efficient storage , with high availability , and tight integration ( emulating the appearance of local drives ) by using a clustered file system combined with local raid storage implemented and infiniband access for high throughput , as is known in the art . fig4 - 7 are a flowchart of provisioned deployment in the diagram of fig3 . referring to fig1 and 3 - 7 , the deployments 112 in the virtual computing ( grid ) environment 100 provide virtual computing services by defining a set of computing classes , such that each computing class is associated with a per user cost , as depicted at step 300 . the environment 100 further includes a plurality of computing service deployments 112 , in which each deployment has a network 500 location and is operable to provision at least one class 144 of computing services , as shown at step 301 . each deployment 112 thus defines a plurality of computing classes 152 , 154 , 156 such that each computing class is further associated with a resource cost and a performance factor , as shown at step 302 . in the example arrangement , the computing classes 144 include , but are not limited to , a terminal server class operable to support a plurality of users on a common operating system in a shared memory pool , as depicted at step 303 , a hypervisor class providing a dedicated os and memory allocation to each user , disclosed at step 304 , and a grid class providing high performance computing resources substantially greater than the hypervisor class , as shown at step 305 . upon a request from a user device 120 , the invoked deployment 112 identifies a computing service level corresponding to each particular class 144 , such that the computing service is provided by one of the plurality of computing services deployments 112 - n via the network 500 , as depicted at step 306 . the environment 100 associates a fee with each of the computing services , according to class 144 , in each of the computing services deployments 112 , as shown at step 307 . the ongoing environment 500 accumulates a usage history corresponding to each user 120 in a set of users , in which the usage history is indicative of the computing demands of each user 120 , as shown at step 308 . the provisioner 134 analyzes the computing demands to define a user profile 142 for each user 120 , in which the computing demands are indicative of a provisioning cost of the user 120 , as depicted at step 309 . the policy 186 defines a set of rules 188 , such that the rules specify overprovisioning and underprovisioning thresholds , in which the rules 186 balance enterprise cost with user satisfaction to balance overprovisioning and underprovisioning , and further that the computed provisioning level ( class 144 ) is independent of the provisioning level of other users 120 , as disclosed at step 310 . the policy 186 reflects the management philosophy of the enterprise towards user provisioning . while the best fit metric 136 strives for optimal efficiency , this management philosophy may augment the best - fit rules to err on the side of cost control or high performance . accordingly , the environment 100 defines the best fit metric 136 in the policy 186 , the policy 186 having a set of rules 188 , in which each of the rules identifies a computing performance concern and a resource cost concern , such that the rule further specifies a tradeoff threshold between the performance concern and the resource cost concern , as disclosed at step 311 . in the example configuration , the computing performance concerns include allocated processor speed , allocated memory , and allocated disk space , generally indicative of parameters which proportionally increase the level of provisioning to the user 120 , as depicted at step 312 . the resource cost concerns include help desk calls , equipment requisitions , and external grid computing requests , as depicted at step 313 , and generally denote factors that increase cost . the rules 188 , denoted in an example form above , strike the tradeoff between these concerns as codified in the best - fit logic 136 . upon a request to provision a user , responsive to a user 120 request for an environment instance 132 , provisioning further includes , therefore , comparing the user profile to a provisioning policy 186 , such that the provisioning policy defining a best fit of computing resources to user demands , as shown at step 314 . the best - fit logic 136 implements the provisioning policy by defining a balance between overprovisioned and underprovisioned users 120 , in which an overprovisioned user is associated with a higher operational cost than an underprovisioned user 120 , while an underprovisioned user may be associated with a higher support cost than an overprovisioned user , as denoted at step 315 . in provisioning the user , the operational cost encompasses costs of providing the user with computer processing capability , while the support cost encompasses the cost of responding to user inquiries of computer processing capability , as shown at step 316 . thus , an overprovisioned user receives a greater share of computing resources than an underprovisioned user , in which each user associated with a provisioning tradeoff threshold , the tradeoff threshold indicating the lowest operation cost supportable without increasing the support cost , as depicted at step 317 . the provisioner 134 resolves these competing ends by evaluating the feasibility using a best - fit metric ( logic ) 136 , such that the best - fit metric 136 defines a cost effective provisioning level for the user , as shown at step 318 . this includes , at step 319 , evaluating the feasibility of the computing service ( class 144 ) identified for each user 120 , such that evaluating includes the network location of the computing service location ( i . e . where the deployment 112 is located ) relative to the particular user , as depicted at step 319 . each of the deployments 112 is operable to invoke the connection broker 124 to provision the user 120 on another deployment 112 , if costs and / or network distance deem it more effective according to the best - fit logic 136 . the classes include a grid class 156 , as shown at step 320 , which may denote an external invocation of computing resources , effectively contracting out the need for computing ability , usually because of extreme demand and / or a temporary nature of the resource need . such a circumstance requires identifying internal and external provisioning sources and costs thereof , as depicted at step 321 , and computing a feasibility of external provisioning , such that external provisioning includes provisioning in the grid computing class 156 , as disclosed at step 322 . the grid may be considered separately from “ on board ” classes provided directly by the deployments because of the relatively higher cost than obtaining the same processing resources from the hypervisor 154 or terminal server 152 classes , usually due to consideration of the impact on other users 120 . accordingly , the provisioner 134 selectively provisions the user 120 in the grid class 156 based on the computed feasibility , as depicted at step 323 . following the comparison at steps 314 and 320 , the provisioner determines if the user is misprovisioned based on the comparison , in which misprovisioning is indicative of a user having resources inconsistent with the user demands indicated by the user profile , as shown at step 324 . accordingly , a check is performed at step 325 and the provisioner 134 selects a different computing class 144 for the user 120 if the provisioning policy 186 as implemented by the best - fit logic 136 is indicative of a misprovisioned user , as shown at step 325 . if the user 120 is misprovisioned , control reverts to step 308 to reanalyze the user 120 demands . otherwise , the instance manager 150 provisions the user in the particular computing class based on the user profile , the per user cost and the provisioning cost , as resolved by the best - fit logic applied to the current usage indicated by the user profile , depicted at step 326 . the user 120 continues via the provisioned environment 122 , while the provisioner periodically reanalyzes the computing demands to selectively reprovision the user 120 , as depicted at step 327 . thus , the provisioner 134 selectively modifies the computing service ( class 144 ) of the user 120 based on the evaluating , as shown at step 328 . such periodically reanalyzing occurs upon triggering events including threshold specifying at least one of page faults , response time , and cpu utilization , all of which are typically associated with an underprovisioned user , as depicted at step 329 , as well as other events which may denote an overprovisioned user , such as upon logout or periodic time intervals . control then reverts to step 308 pending the next reevaluation . those skilled in the art should readily appreciate that the programs and methods for provisioned virtual grid computing as defined herein are deliverable to a user processing and rendering device in many forms , including but not limited to a ) information permanently stored on non - writeable storage media such as rom devices , b ) information alterably stored on writeable storage media such as floppy disks , magnetic tapes , cds , ram devices , and other magnetic and optical media , or c ) information conveyed to a computer through communication media , for example using baseband signaling or broadband signaling techniques , as in an electronic network such as the internet or telephone modem lines . the operations and methods may be implemented in a software executable object or as a set of encoded instructions for execution by a processor responsive to the instructions . alternatively , the operations and methods disclosed herein may be embodied in whole or in part using hardware components , such as application specific integrated circuits ( asics ), field programmable gate arrays ( fpgas ), state machines , controllers or other hardware components or devices , or a combination of hardware , software , and firmware components . while the system and method for provisioned virtual grid computing has been particularly shown and described with references to embodiments thereof , it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims .