I just want to chime in on the whole Vista thing. I run Vista Buisiness 32bit on my new machine (amd athlon x2 5200+, 2gig corsair xtreme ram, geforce 8800 gtx (pcie), nforce 590 SLI AMD mobo). This is definitely not a gaming OS in its current state. By its very design nature, even if you tweaked it as best you can, virtually every game will run 10% slower than XP with SP2 because of the way graphics drivers are dealt with in the new OS and its kernel.
Will future graphics drivers updates remedy this? I guess we'll wait and see. Afterall, the Nvidia ones are barely out of beta. I can't comment on ATI, but from game performance analysis charts I've seen on websites I'd say you ATI owners are in the same boat.
If not for some of the components in my new PC being cutting edge, I imagine gaming in Vista would be near unbearable.
I also experience BSOD from time-to-time, paritcularly when playing quicktime files and trying to multitask (i don't recommend it!). I love the lynda.com quicktime tutorials but since vista keeps crashing when i'm trying to view one and, say, follow along in Illustrator, i can almost guarantee a crash within 30 minutes. Is it graphics driver related, quicktime related, both, or what, i'm still trying to figure it out.
Then there's teh problem with Aero 'shutting off' when you run certain programs that for whatever reason aren't compatible with it. Realplayer is one.
Overall I find Vista to be far prettier and than XP, but until they get some conflicts worked out (by SP1 maybe?) I suggest sticking with XP with SP2 applied for reliability and gaming.