Get Fraps for checking in game fps. http://www.fraps.com/download.php It can show on screen but also has a handy benchmark tool. My 5850 cut threw source like butter, something screwey here. Unstable overclock on either CPU or GPU can and will hurt you. If you haven't tried yet I'd run both at stock to see how it goes. Drivers 10.12 was working alright for me before I pulled it (5850). PSU problems maybe ? IDK 700 should be enough but OCZ PSU's don't exactly get much high praise around here.
this is the result counter strike source gave me
im not sure how to do this on cod4 although the result should be similar (really good) but during gameplay, it lags like hell
i used catalyst 11.1, the one provided on the installation cd and right now, i downgraded to 10.10 (yes i did uninstall the old drivers and ran driver sweeper before installing the new ones)