MuzzleFlash!
Initially I did use the uninstaller provided by ATI, But it didn't work the way it was supposed to I guess. I wasn't able to install ANY drivers on my computer after that!
I found this link to a very thorough description of the uninstall process for the ATI drivers:
http://www.driverheaven.net/windows-xp-2k-radeon-display-drivers/107447-uninstalling-installing-ati-drivers-properly.html
Haven't been bold enough to try again, since I had so much trouble last time I tried!