R8500 with RH7.3
Ok, no problem here: please, next time select the custom installation, so you will have total control under video options.
Now this is my solution in your case: if you cannot launch the X-Server, after the loading you are in the console, right?
Ok, so write:
Please note that Linux is case sensitive!!!
After this you will find a file named XF86Config in your home directory, or in the directory from where you launched the command.
Now, rename it in XF86Config-4 (note the upper case letters!) and copy it in /etc/X11; if linux asks you about overwrite say yes.
Now launch the X-Server with: startx