3870s aren't faster, they just get really good 3dmark scores. The 4870 is tons faster. Don't let 3dmark fool you. 3000 series cards are really only useful if you are trying to go for a wicked 3dmark score. Otherwise stick with the 4000 series.
Microsoft will have it fixed soon enough. I would say you could probably just get away with turning off hyper threading if you really wanted to. But even with a 10% hit, core i7 is still faster than core 2.
poo not a gtx260. I don't see why everyone recommends them. I can see why you like em Nos, for the 3dmark and crysis scores. But otherwise ati is the smart choice.