System fails to boot after installing new Radeon 9200. What am I doing wrong?

Hello there I've been lurking for a while and thought I'd make my first post. I've recently bought a new Radeon 9200 from MacGeniuses on eBay for my G4 dual 450. I've installed the Radeon update and ATi Displays packages, however with the 9200 installed, the system fails to boot. After the grey screen with Apple logo and the spinner, when it changes to the blue screen, for some reason it just stops booting. Nothing else is displayed, just stops on the blue screen. If I reinstall the original Rage 128 Pro card, the system boots fine. I'm a recent switcher to the Mac world, so unfortunately I don't yet know enough to work out where I'm going wrong. If I boot from the install DVD, System Profiler detects and identifies the 9200 correctly, so it does work. Any help would be much appreciated

Not good news. Here is a scary link from ATI regarding G4 sawtooth Macs:
http://support.ati.com/ics/support/default.asp?deptID=894
You may have to return that card, but contact them here:
http://support.ati.com/ics/support/default.asp?deptID=894

They may not have flashed that card right, I would send it back to them. What happens is they take cheap PC cards, flash them with a Mac BIOS, and then sell them for a LOT more than they bought them for. Sometimes the flashing doesn't work out so well, and they probably don't do too much testing so this is probably why you have a dysfunctional card...