I uninstalled the drivers, But why does the Windows keeps finding the Omega Drivers even after using Driver Cleaner and/or clearing the registry?
There are some files that Windows saves for backup purposes that cannot be removed by any means, except manually, here is how to find them and remove them:
1. Open Windows Explorer and go to the "Windows\Inf" folder.
2. Do a search inside it for "A word or phrase in a file", type OMEGA and click search.
3. In the search results box delete all the files with the name "OEM##.INF", where ## can be any number...
4. Now remove the video card(s) from the Windows Device Manager and restart.
After restart Windows will now detect and use a Standard VGA, after that you can install any driver set.
http://www.omegadrivers.net/ati/ati_faq.php