rastagard, maybe you ought to give Eduardo's WDM drivers a try.....
I would recommend using the "install by hand" that he offers, versus the auto installer. It takes about 5 minutes to configure the Bt848.inf file to match your card.
There are just 2 files you need: the BT848.inf and Bt848.sys file to have Windows load the proper devices and drivers.
......and make sure you remove all the ATI "junk" first.... and start with a clean install of the card.....