I've heard that Supreme Commander has nothing but trouble with Vista, so I've stayed clear. I may give it a try, but it's really not my kind of game anyway.
My sound card is a turdy one, but since I only have two desktop speakers, I've not been fussed to splash out
@Fake - I have never really understood the draw of the Halo series. UT looks damn sexy in the graphical department, though. I would give that a try for sure.
PS - Vista Ultimate with the leaked x86 and SP1 upgrades. I love Vista.