Whoa, I just got mplayer the other day, and it rocks! It will play almost every Video format, with good quality sound and video, AND its easy to install!
I run RH9 (shrike), and didn't have any problems whatsoever. I also configured the file types to play with mplayer from the GUI (an easy task, really - lol) and now it works like a dream
I just thought that I ought to say this, in case anyone is after a good all-round video player for linux
I found the RPM here (although there is also the source available too) - http://www.mplayerhq.hu/homepage/design6/dload.html