Do you got the recently released ATI drivers? They have given 5-10 fps in GRAW depending on whom you ask. I got a similar setup as you (no OC) with the same FPS but with all settings at high.
ive got a Athalon 64 3000 1Gb of Ram and a 7600GS and i play everything on high and it merrily flies along on 1024x768 quite happily at about 45-50 fps.....