Try the modified ATI/Nvidia drivers from
http://www.ngohq.com
The lastest one is based on Catalyst 7.3. I'm positively suprised about the difference in performance: Before, I couldn't get Gothic3 and Stalker to run properly with my new card and all standard drivers I tested. They were unplayable - stuttering like hell, even on the lowest possible setting. With the NGO drivers, however, they run smoothly on max settings with no apparent problems so far.