Nope Im on a 22" 1680 * 1050 and getting around 80fps average, never drops below 60. Both 5850s are at stock. I happy with the framerate but want to play at Ultra/High settings, I think the only way is to sell my 5850s and get a 3GB GTX580, but IM holding fire until the final release as it may be better optimised
I'm not 100% sure but I don't think you need a 3GB GTX 580 to play at that resolution. You'll probably ok with a single GTX570?