Probably not much in the short term. As drivers and such improve the performance in games can improve since right now I've read that game performance on Windows 7 is similar to the current Vista (a little better or a little worse depending on the game).
There probably wont be any huge things happening unless tons of people start switching over to Windows 7 or Vista and getting newer hardware that would make use of the new graphical features.
With the way PC gaming is going with crap like Modern Warfare 2 and Microsoft's attitude with Games For Windows Live, who knows. Can the good developers keep it going?







