|Ummm.. Don't buy ATi anymore? heh. |
But seriously, their drivers suck beyond almost anything else out there(I mean, who thought it was a "good" idea at ATi to build their drivers with .NET? 0_o). You will need to boot into windows either in safe mode, or with the original card installed and completely uninstall the drivers, then and only then insert the new card and boot.
If this doesn't work, come over to the Dark Side and join the Nvidia crowd.
PowerMac 9600(1 ghz G4)
ATi 9200 PCI