Hrm. I don't know specifically, but the 7600GT is supposed to be noticably better than the 6800 series. By "noticably better" I mean it has better FPS doing things like FSAA, aniso, higher resolutions, and in general it does more "goodies" for the same FPS. Something along those lines.
EDIT: The reason it does those "goodies" better is the GPU
EDIT2: I'll list my FEAR settings later tonight, and how much the FPS was on the "test configuration" button. It should give you an idea. I could barely run FEAR at all on the same system when it had a Ge4400 card in it. I had to turn everything off, use the lowest resolution, AND pixel doubling!!