Sorry mate, AMD and NVidia shaft us by having all these features we never use in their cards so they can charge more money for less performance.
I'd say the AMD 6850. I don't know American prices or w/e, but you can get a few of 'em over here in the UK for £90.
I've got a 6670 DDR3 Meself, it cost me £60 and it doesn't even play Fallout 3 at max settings above 30 fps. With Skyrim, it doesn't even get passed 35 fps at Medium settings.
Go wit' da 6850.