Will Call of Duty 4 run well on low configuration

You need to adjust a LOT of settings to get the most out of your PC. Things such as program priorities (in task manager), graphics card priorities/settings, and general Windows settings come into play.

If you have too much detail etc, it will run slow. Turn it down a little (turn certain things down) and it will run great, with hardly any visual difference in detail.

The best way to find out what your computer can handle is play around with every single setting you can find.