I'm playing COD4 on a Celeron D 2.93GHz CPU, 800MB RAM and a ATI Radeon 9550 256MB Graphics Card. I have to say it is playing incredibly well! It is ever so slightly laggy at first but once the machine gets warmed up, man is it good and i'm even playing it in HD so even better! And the mulitplayer is brilliant as well! Im thinking of getting a good dual core processor some time, make the experience even better. Yes it is hard though with all the new hardware that's coming out all the time. Hard to keep up with whats the latest and new games are often always built around this new hardware so it makes it difficult when we want the very latest new games.