You will also want to get a PSU: OCZ 520w Modstream
. You can't go wrong with that. Matter of fact, any other brand-name PSU would be fine.
You might actually be able to get away with that case PSU, but there isn't much protecting it in the event of an overcurrent or undercurrent.
As for your BF2/HL2 question, a 6600 GT will easily be able to handle them at medium if not high. A 6800 GT will surely be able to play ANY game out right now at full blast settings with a very decent framerate.
What core is that CPU? A better option would be the 3700+ San Diego
. It's a newer core, found on the faster AMD processors.
I thought it was called Pixel Shader 3.0.