I'm not sure that COD4 will even run on the laptop. I looked up the minimum system requirements and they say that a Radeon 9800 Pro is the bare minimum for the game and that's a desktop card. Even if you could get the game to play, I don't think it would run all that smoothly.
You don't really have much to lose by just installing the game and giving it a shot. The worst that's going to happen is that you will waste 30 minutes of your time on a failed experiment. It's not like your laptop is going to explode, lol.
Well, I remember playing it on a 7200GS (which is worse then the 7200GT) so... The only problem is, I don't have it anymore and I need to go out and get another one. Just didn't want to waste the money.