welcome to linuxquestions.org by the way
As far as I know the DELL E772C is one of the available monitors that should be working fine or at least detected by RH 9.0.
If you're telling me that a generic setup wouldn't work for anything besides 256 colors I would do the following.
If you know someone that has RH 9, I'd go to his system with your monitor and test it there...see what comes out...if it works on his system, you might either wait for other forum users to reply to your post, or just simply reinstall the whole things if you can't wait to use X windows
You might even wanna try it on a windows system *cough*, just to see if you can retrieve more than 256 colors off that old monitor.
Hope that helps!