Compiz looks ugly? try this...
So now that I have an 8800 GT, Compiz has no excuse. Why did it look exactly the same as when I had a 7600 GS?
Here's what fixed my problem. In compizConfig, go to the "general options" page. Click on the "Display Settings" tab.

Make sure you uncheck 'detect refresh rate', move the 'refresh rate' slider to 60 (or more depending on your monitor), and enable the 'sync to vblank' option.
This got rid of my slow framerate. It also got rid of an issue where the windows looked distorted when they were moving. (it's hard to describe, almost as if half the window was shifted to one side by a pixel or two, so the edges looked jagged but the contents looked fine.)
There you have it. I hope this was helpful.