Compaq Evo and Radeon 8500 driver issue

I’ve got a system here that is a box compaq evo d500. We installed a Radeon 8500 vid card in it, and it won’t accept the drivers. It blue screens when logging into windows. The OS is WinXP. It gives us the option to go into safe mode, but when we do that, it loads the standard vga drivers. No matter what we do, the sytem just won’t accept the drivers–any ideas?