BF:BC2 bad performance

My specs:

AMD quad core
nVidia 8800GT 512MB (overclocked)
4gb ram @ 800mhz
Win7

In other words a better PC than the recommended requirements are for BF:BC2.
However, i have all settings on low, no AA, and resolution @ 1280x800, still i only get 30-40 fps.

I can play both BF2 and cod4 @ max settings, with good fps, but this game just wont run smooth.

Any ideas? Its focking annoying.