I agree there could be stuff left from the vodoo3
it usually works best if you set it as a standard VGA, turn off
replace graphics card and machine should find the new card
if not set new card as standard VGA and reboot.
It is a good idea to run glsetup.exe (search the web for latest ver.)
I did with my ATI 128 rage 32meg  + tweaking
bench with a simple 3Dbecnh program increased from
16 to 66  4x !!!