I have a Radeon 7000 installed in my Beige G3 running OS X 10.2.3; plus: Sonnet ATA 100 and Sonnet USB/Firewire cards. All work fine. Any compatibility problem is definitively fixed since 10.1.5.
Before 7000 this beige had a Radeon Mac Edition now moved to a PM9600.
When playing a dvd in full screen mode frames dropped, while with Radeon Mac Edition all went fine. I don't know when this "problem" showed up. It could be from cards swapping, Mac OS X updates, firware updates; but I don't play dvds on macs and quartz is definitively boosted (while QE not enabled

).
If you can find a Radeon Mac Edition buy it. If not, buy a Radeon 7000.
NOTE: when booting the screen remains black (stopped) until OS X reaches "network initialization" or so. This is a well known Radeon (any PCI version) + beige issue. So don't think that your new card is DOA. Wait an listen to your drive (it's a sign that OS X is booting)
Bye
Sam
All check out dvds frame drops by swapping cards again... stay tuned.