I have been using Vista Ultimate 64 since it came out along with Vue 6 Infinite 64 and it works like a dream.  So much so I have 3 of my computers running on it now.  However, I can't speak for games and things like that as I only use them for rendering, the occasional letter and a bit of post-working in photoshop. 

"I am extraordinarily patient, provided I get my own way in the end" - Margaret Thatcher 1989