Need opinion on new card

I build my current PC a little over 2 years ago when intel's i7s had just come out and I've been noticing over the last year that the GTX 275 i have just isn't cutting it for me anymore. Ill probably wind up building a new system in another year or two but until then I'm gonna need a new card to hold me over until then. My main concern at the moment is Skyrim, BF3 and Kingdoms of Amalur. I'd like to play them at close to max settings, maybe not BF3, and still be able to get some life out of it for another year or so. I've been looking at the GTX 570 but i'm not sure if i even need that if a 560 or 6950 will work for a little over a year. Here are my specs

Asus p6t deluxe v2
i7 920
GTX 275
6GB memory
24" monitor
I always play games in 1920 x 1080. Any opinions will be appreciated.