I owned an HD 4650 before and yes it would most likely run it max settings 1680x1050 no AA. Or 1280x800 max 2xAA. That was how I ran it. 1280x800 max settings no AA ran silky smooth. And your CPU is better than the one in my old HD 4650 PC. It will run BF BC 2 much better than on low settings lol. ANd It will max out L4D2 ... So yes you can run all those games properly. But if you keep the res below 1680x1050 and with no AA. L4D2 would probably run with AA on.