Although this may or may not be applicable, try Windows Update to see if there is a new driver for the ATi. It worked for me, though I'm using an AGP version of the same card. I had tried downloading drivers and software from ATi and nothing else was working until I got an error message and submitted it to MS and they immediately popped up a solution and said it was to download the new driver from Windows Update.
Can't hurt to try.
Part of my problem was that I was building a new system and needed to put in a different PCI video card until I installed the AGP drivers and I did Windows Updates without the AGP card installed. Slightly different than your case. (OS disk included SP2) Look in the hardware section to see if there's a driver.
Edited by Herk, 28 April 2005 - 11:50 AM.