The 2.4 Catalyst drivers seemed to have raised the performance I get.
Only problem I see is the same problem I've had from the beginning when I first bought my 8500, during the fill rate test on 3dmark....I get split second "pauses" where the textures just stop moving..then start again....seems like it's not a driver issue, but a problem somewhere in my system...I see the same "pauses" during some games as well...( possibly due to the fact that My MSI 845E MAX2 BLR board won't allow me to adjust the AGP aperature size and has locked it at 64Mb....actually..all the software I have used reports the AGP aperature at 55Mb...when it SHOULD be 128Mb )
Other than that, ATI has got their act together as far as drivers, and if your seeing a huge performance drop just by changing drivers, ( like the loss of 30+ FPS ) then something with the install went wrong, or some sort of corruption took place...( like within the registry...a file..ETC...ETC...)