Are you using the most recent ATI drivers version 11.8? As I understand it, the 11.6 and 11.7 weren't too good.
Please read the thread about optimal settings both in the CCC and in-game here:
http://forum.1cpublishing.eu/showthread.php?t=25543
If you're flying a Spit, turn off the mirror. It is broken anyway so quite useless.
As CoD is a sim that has to compute much more data than an action game like WoP, it has less time to calc the eye-candy, so don't expect to run CoD on the same graphics level than WoP.
My system is not so different from yours, just that I have a faster GPU and I can run CoD @1920x1080 with all options set to the highest settings, only textures set to high and shadows off. So I am confident you could tweak the settings to absolutely playable settings.