[Jonwall]

Vista 64 hands down, the porformance versions of xp give you like 5% more fps in games if that and seriously degrade the os experience outside of gaming. With that kind of a rig vista should be what you go with anyways trust me, it takes some adjusting but once you get used to it xp seems like crap. My main hdd died awhile age so i installed xp again just for fun, i had more crashes in 3 days than i had in vista in over a year. NEedless to say i uninstalled it and installed the far more stable and reliable vista x64.