The CPU won't be your limiting factor in games (possible exception GTA4), so that won't stop you hitting max settings in any game - tick.
4GB of RAM is more than enough for any current game out - tick.
8800 GTS OC 512mb - not the best card but certainly not slow either. Not familiar with the model but looked for a benchmark for Crysis as that's still one of the hardest ganes for a GPU to play. If you can play Crysis, you can play anything: http://www.tweaktown.com/articles/1234/nvidia_geforce_8...
Depending on the resolution of your monitor, it might be able to play with everything on High, or you might have to settle for Medium.
Crysis is an extreme example, so being able to play it on High (without AA) on 1280x1024 or Medium (without AA) on 1920x1200 means you should be able to run most games with all settings maxed out, you just might have to have a play with the AA settings to find one that looks nice without slowing down.
Overall, nice PC that should keep you happily gaming until the DX11 cards are cheaper/in their second generation.