If you didn't figure out the actual reason it was asking for the OM disk, its because you had checked the "Install OpenManage Server Administrator" while using SBUU.  Unchecking that would not have asked for an OM disk. There is no such thing as "bloatware" on servers.  All OEM's recognize the importance of servers being as pristine as possible, so nothing is included.  Three things from the Support Site that you should install on every server, and should have no affect on services or applications running on the server: If you install nothing else, install OMSA.  Everything else from the Support Site serves a purpose to your organization - whether or not you might be able to benefit from what it offers is up to you to learn more about it. For what reason would you convert the disks to Dynamic?  Dynamic has its place, but only for a very few things.  Unless you need it specifically for some reason, I would keep them as Basic.  As far as the RAID is concerned, it is "ok" to convert them, if needed.  Just don't convert them to create a software RAID in the Windows software.  
I have just taken delivery of a T310 without an OS. The system only came with a disk described as Systems Management Tools and Documentation (SMT) and a small hardware setup manual but there was no mention of  how to load an OS. I already have a SBS2003 OS ready to install. However if I load the SMT disk and boot the server all I get is the message 'no operating system found'. I did not see if it accessed the SMT disk during the boot sequence. I haven't tried putting the SBS2003 disk in and try booting again because I am not sure if this is the correct thing to do. Does anybody where I can find the proper procedure for loading an OS to include the management software and tools available from Dell ?
Procedure for installing OS on clean Poweredge server