Turn on Temporal AA, it will increase image quality. It alternates the AA sampling pattern each frame, and as such you won't see a diferance in screenshots, but you will in real life.

Some Artifact detecting programs detect Temporal AA, so if you're going to be doing any tests for artifacts make sure to turn off Temporal AA.

Temporal AA has no performance hit, so leave it on.

Catalyst AI is just some optimizations, I don't know exactly what they do but I leave it at high. They probably increase fps by like 0.5 fps.

Adaptive Anti-Aliasing improves image quality by Anti-Aliasing textures. Leave it on for better image quality, while leave off when in a really hardcore game so you get a higher frame rate.

ATI overdrive is an overclocking utility. Using it can fry your video card, increase power consumption, and void your warranty.

However, if used correctly you can gain a few fps. I leave it off, but if your game try it.

ATI overdrive allows you to change core / memory clocks, and change voltage. External tools like ATI Tray Tools have extra ATI optimizations and even allow you to alter your memory timing.