BF3 is highly dependent on your GPU. There have been numerous reports that GTX570+ cards have yielded better results than lower/mid end cards. You may find some FPS problem. But at your resolution, GTX560 Ti and 6950 are the best options.
Totally understandable, but either one of these cards should surpass the power my crossfire setup im running with my 4830's, correct? From what ive read on the specs and just because of my love with ati im leaning towards the 6950