I'd recomend a couple of things.
Go get a good driver cleaner, clean everything out. Reinstall cat 4.5's, & direct x.
Make sure your booting CLEAN!
No office, fast find, spyware, antiviris, etc.
Reboot before you start AH.
You may have to tweak that card a bit, I'd suggest the rage3d tweaker.
Its posted on the msg board here someplace.
Get PROactive. HT provides the software, the rest is up to us. If EVERYONE had the exact same problem,
then it would be his problem. Since some of us are obviously doing fine the burdens on you.
BTW I'm getting 38 fps in tower & 60's 2k up with an elcheapo ati 9000 pro 128mb card that was only 100$ 16 months ago.