The RageII should support the Apple/ATI OpenGL extensions. But, it's not going to be fast as it's not hardware accellerated. Note that some games require hardware accelleration (for example, Tomb Raider).
It's much better to get a Radeon 7000 PCI as mentioned above. (I have one in my Beige MT and OS9.2.2 flies, and it actually makes Panther much more usable.)
