Here's the update on the Vista game PC. I ditched Microsoft technical support and decided to start over again. This time a bought a 10,000RPM boot drive and installed the O/S on that drive, saving the 500G RAID 0 drive for applications (games). I first installed the OEM copy of Win XP MCE I had originally build the system with. I didn't bother to install any of the service packs or even authenticate it, in fact I disconnected it from the Ethernet to make sure it didn't phone home or get infected. Then I immediately installed my Vista Premium upgrade edition. Everything went smoothly. I then installed all the latest drivers. And it's doing very well. The only problem I've had has been standby issues with the ASUS motherboard and Vista. Occasionally the motherboard hangs in an ACPI state. I've also noted that the motherboard occasionally won't cold boot until I reset it or power cycle it. That is definitely a motherboard issue.
Now I've got some of the best new games installed: Bioshock, Valve's Orange Box, World in Conflict, UT3 demo, and the Crysis demo. My favorite "old" game, Battlefield 2, won't install though. I need to figure that one out.