Head over to box on the left with the System Requirements : Command & Conquer 4: Tiberian Twilight - Wikipedia, the free encyclopedia
They were trying to make it playable on as many systems as possible ( There's a point of diminishing returns for doing that. ) but check out the patches for the game.
It's possible an update may improve your visuals.
Asus M4A77D, 64 X2 6000+, 4 GB Corsair DDR2 800 ram, Radeon 5770.