I use Mesa drivers for my ATI Radeon 9000 (with fglrx I have a problem with Blender). But interesting is that I have better test results with Mesa driver than ATI fglrx :
Xorg 7.0, KDE 3.5.1 and I use ATI drivers 8.23.
GL_shadow: doesn't work GL_pointz 441.2 GL_blit 915.6 Fake 351609.4 GL_blit_ext doesn't work GL_smoke 392.2
And now I have KDE 3.5.3 (and everything from testing):
GL_shadow: doesn't work GL_pointz 326.4 GL_blit 910.0 Fake 891754.4 GL_blit_ext 905.4 GL_smoke 409.2
GL_shadow doesn't work.