Xconfigurator and Xfree86 need to enable DRI 3D rendering
ATI Rage PCI/AGP, ATI Rage Mobility P/3/4, Matrox G450
XFree86-4.0.2-11 and later do just that for all r128 cards.
I believe Xconfigurator does as well, but that would have to be filed
G450 DRI is disabled and will remain so unless Matrox or XFree86 team
gets DRI working on the card.