Well the word on Omega drivers is they are optimized for gaming, ie: better texture quality stable frame rates with AA and AF utilized. I dont touch those nvidia benchmark programs after all the bias I hear they have to their sponsors. What you need to do is just go ahead and install the omegas and test them for yourself. Its simple 10 mins process to correctly uninstall/intall new drivers.
Omegas uninstall just fine.
Here is a walk through on how to properly uninstall reinstall drivers.
Walkthrough In the end personally I don't see any difference in using the Omega drivers.
How I really see a difference is using
Rage3d Tweak And following this tweak guide.
Guide After changing these settings stated in the tweak guide, with AA and AF the blurry text cleared up for me.
Another thing to do that acutally bumped up my game performance and FPS is defragging. If you are running XP you should be defragging at least once a week if you are a gamer, NTFS needs it.
I don't have anything else to say, I'd suggest you take these questions to the driver heaven forums, those guys know ati drivers and performances inside and out.