The first thing you can try is to install the old drivers for your videocard, iff you havrom CD of your videocard uninstall the currfent drivers and install from the CD, then try COD4 again.
You told us that you updatet the drivers for Bad Compagnie, after that you have problems with COD4, it must be the drivers, when you uninstall the new drivers and install the old one COD4 must be ok. I sat back looking at the stars. And I began to think, ...............where the heck is my roof ?