All the drivers necessary for a Radeon 9800 Pro or XT are already in the OS.
Unless you made an installation error (not properly seated, static issue, broken or cracked capacitor) the card should be plug and play.
Could be the card was damaged or died in transit?
As for not being able to reset the PRAM, this can occur with non Apple keyboards. Try a Open Firmware boot (Cmd+Option+O+F) and reset the NVRAM:
Apple states the computer will restart but that doesnt happen.
That's a NVRAM reset. Resetting the PRAM makes the Mac cycle through the chime process. Hold the keys until hearing a second chime, then release and the machine starts with the PRAM settings reset.