CS 312 -- Jacob Lundberg
Info on the ATI video cards
Technical Specifications
The current list of supported cards in Xfree86
ATI Adapters README for XFree86
It seems that RedHat 6.0 uses XFree86 3.3.3, so it might be worth trying 3.3.5, which was just released. However, some ATI chips (like the Rage 128) are unsupported. See link three on the ATI README.