COD is a great game that is easy to play online. I don’t play Single Player anymore. I only play the PC version. I have not heard good things about the console version. COD requires a fairly decent video card. Nothing major. I was able to play COD 1 on a Radeon 7000. My kids have a low-end card and it plays COD2 well. I can usually be found on the MoG servers.
Pick up the demos from Fileplanet and give it a shot.
I'm more into twitch games that I can pick up, play with for a bit, then put back down again. (Comes from the hours required for the job, and having little kids...) I've been into MAME (Multi Arcade Mission Emulator) for awhile. It grabs the ROM files from the old arcade games (Asteroids, Space Invaders) and puts them into an on-screen playable emulator.
Nothing like playing the old games from the 80s. And, I can "feed a couple of quarters in", play for a few minutes, then walk away without getting sucked into playing for hours. It's a pleasant, brief distraction.