MP3 player support was removed from the upcoming Red Hat 8.0 due to licensing legal concerns.
http://www.gurulabs.com/downloads.html This page has an easy to install RPM that contains only the MP3 plugin for XMMS. They also have links to more information regarding this MP debacle. Please remember this URL and tell all future Red Hat 8.0 users, because they may be a bit annoyed that MP3 wont work out of the box anymore. http://news.com.com/2100-1001-959434.html This CNET article has a ton of information about this upcoming Red Hat release, including this MP3 issue, Bero's resignation from Red Hat over the Gnome/KDE unification controversy and more.