From the testing i've done between Vista x86 and Vista x64, there is definitely better performance in x64. Sometimes the FPS are identical, but x64 seems to handle games better in respect to keeping the framerate from dropping:
i.e. Vista x86 - Max FPS = 100 Min FPS = 74
Vista x64 - Max FPS = 103 Min FPS = 83
Something along those lines....
r2rX
