I had some problems with my rage128 (rh 7.1) as well - GL support for the 
rage128 line isn't in Xfree till version 4.0.2 - check that first (XFree 
-version).  Secondly, check the /var/log/XFree86.0.log - look for any lines 
that have a "(EE)" at the beginning - I had one where the r128 module it was 
trying to load was linked against a different version of the XFree libs, and 
thus wouldn't load - thus GL wasn't working (for me it would just _not_ run, 
or run in SLOW software mode).  At that point I just recompiled the DRI 
modules and all was good.

Here's the page(s) I used to get it all working:

http://dri.sourceforge.com 
http://www.lokigames.com/support/gldrivers/

-dallas