I haven't read all the replies but most of you seem to imply that anything equal or superior to a 560~6950 is way overkill, i disagree... Is high resolutions the only aspect that defines a good graphics card?
Actually, as far as i know, high or low resolutions are affected mostly by the amount of vram, obviously all those extra pixels will have to be processed by something but it won't be nothing special to the gpu. Now how about FX? Aren't you guys forgetting AA, AF, Ray Tracing, DOF, Shadows, Shaders, Physics, Tesselation and plenty of other highly demanding effects... Do you guys really think that because he's going to play on lower resolutions these FX will be less demanding?... Or resolutions are everything to you?
Try to max out Crysis Warhead or Metro with DX11 enabled and all it's features with a 800x600 or even 640x480 resolution with a 6770 and you'll see what i mean...