Well Still having problems with cod4 multi and win 7. So far all the pc's we put win 7 on are not capable of playing multi without getting kicked back to the menu. COD5 works great. I really do not want to reinstall vista as I will have to transfer the game profiles.
It's a beta OS, don't expect everything to run properly. Also, if COD4 does an OS check when you go on multiplayer, it mightn't detect Win7 properly, but that's just a guess.
You're going to have to format and reinstall anyway once Windows 7 comes out (if you're planning on buying it), might as well back up your game profiles and reinstall Vista on the mean time
Microsoft does have an official Windows 7 Support Forum located here http://tinyurl.com/9fhdl5 . It is supported by product specialists as well as engineers and support teams. You may want to check the threads available there for additional assistance and feedback.