A maximum resolution of 1024x768 pixels on low/medium settings ... may be possible. If not playable, lower down the resolution. Source engine is really well-optimized, so give it a try.
yes 5on5 pcw around 30-40 fps inside around 60 it feel smooth but playing deadmatch with more than 20 players is unplayable. but you should buy a new computer to enjoy game.
there's a bunch of them, but I kept in mind so gonna full my disk with those games like cod mw's, doom 3, quake 4, nfs games and co. oh and just found a game from 2011, people can fly company made it so it must be good : bulletstorm.:D
theres no such thing as "with amd you will have problems"
though phenom 555 x2 is not near top, it still is a good proc (enough for GO).
Phenom x4 955 Black Edition or any bulldozer (specially fx4170) should do fine.
I said that because my friend with same cpu is having huge fps drops from 220 to 70, than it sometimes stay at 80~100 for 4 minutes and than again back to ~200, and they have almost same setup...