For noobs out there that don't know where to save the config you save it in your CoD4 'profiles' folder. On my computer this is located at:
C:\Program Files\Activision\Call of Duty 4 - Modern Warfare\players\profiles\Iain
Of course, you could have installed CoD4 on a different hard drive and your profile name wont be Iain...
Shout out to Infected for giving me a good config to work with
Here is the link to download it from: http://rapidshare.com/files/69856638/config_mp.cfg