Yeah, the Rage is greatly supported. It even has kernel-level accelleration support.
The X.Org driver is called "ati." You should check your kernel config to see if DRI is compiled in, and load the driver corresponding to the Rage 128. Once you do that, and have xorg.conf set to load "dri", the card should work wonderfully (well, as good as it can, it's an old card.