I have Vista installed right now, 64bit ultimate. I am able to play all of my games (i havtn tried some of the older ones) but all of the ones i was into since vista was released work.
The only times i have run into problems was with Norton antivirus (it has sinced been fixed), DivX Converter (i havnt checked if its fixed), and I was not able to play C&C zero hour from my XP install without reinstalling it on vista.