When installing RedHat 6.1 on my Digital Celebris 590 system my video system was not properly detected and no option offered for manual entry of the chipset info. Final result was a text mode only installation and no driver for the S3 864 chipset. SuperProbe from the command line does properly detect the the video system, and, after a deeper look at Linux software installation than I intended, I have a working X window system.
This issue is resolved in the latest beta installer.