In case change your VGA, look at least for Geforce 660Ti.
And if possible upgrade your RAM to 8 GB - this is "cheap".
I am inclined to believed that Geforce is a better buy for CloD than Radeon.
I exchange one old Geforce GTX 250 for HD 7970 and now have annoyed graphical
bugs with this VGA: the "magic square" borders of LOD in middle of map, band in beaches
and river banks, drop of FPS with TF pach...
Sokol1