I believe that video capture (tv -in) is not yet supported through the ati drivers.
You have a couple of options as far as achieving at least 3d acceleration.
XFree 4.3 and 4.4 have a radeon module which worked reasonably well with my Radeon 9000 Pro... Yours is a few generations beyond me. You'll want to do some searches on radeons and drivers. The ati drivers will support your card. They can, however, be a real bear to install for newbies. It's not that hard in the end, and you'll gain some experience in hand-configuration (which is very useful in linux).
Your first step should be to hop over to
www.ati.com and grab the linux drivers for your card. They come in an rpm which you can install on redhat very easily. There is a HOWTO on the drivers page.
Good luck
--Shade