Via Bootcamp I put Windows 7 Ultimate 64 there.
This is all to play a game.
I think the results are pretty evident.
Under XP I could only set the graphics a little past half-way. Under Win7 I can set them all the way to the top.
Pictures from XP
Kfir C2 in Flight.
Pictures from Win 7.
Kfir C2 Cockpit.
Be sure to click on the pics to see them larger and to see the differences more clearly. 1920x1200 is the native resolution I am running.