vWorkspace will interface with Hyperv, ESX with vCenter and Odin Virtuozzo to deliver VDI. You can get some functionality of vWorkspace to work with Xernserver, but you will not be able to use many features, such as  power management and provisioning..  But more importantly, it is not a platform we quality test with vWorkspace so we do not handle support for it.   Kelly Craig Product Management - vWorkspace
Vworkspace and Hyper-V are the cheapest combination for VDI but is there a version of vworkspace that runs on xenserver 6.5?
Vworkspace on xenserver