Catalyst 5.7 Drivers @ AnandTech
 

"Until then, though, for those with budget ATI cards, there's some good news. If you use an older ATI card and have already downloaded and installed the latest catalyst driver (catalyst 5.7), you may notice some games playing a little more smoothly for you. After talking to ATI, we learned that the secret behind this is something called HyperMemory."

Check out Josh Vennings article on ATI's Catalyst 5.7 drivers over at AnandTech.