The latest Radeon drivers for Windows 2000 are significantly better then they were at one point in time, their still not 100% though, and until they are you'll likely have somewhat better gaming performance under 9X.
They are improving though, and their much more reliable, and performance is getting closer to what it is under 9X.
Most of the more popular games tend to perform pretty equally between them now but in other games you'll still lose about 10-30% compared to Win9X.
Still, like I said their improving, and they are at least useable now.
Compatbility seems pretty good, and the rest of the cards capabilities such as DVD etc. is already up to the standards under 9X.
I'd suggest dual-booting with Win2k just for the pure stability, reliability and security Windows 2000 offers. You can always boot back into 9X for your gaming.