The short summary

You only need to install this rpm to be able to play mp3's in Red Hat 8 / 9:
xmms-mpg123-1.2.7-21.i386.rpm

Complete set of xmms rpm's for RedHat 8 and 9

This is a set of RPM's for Red Hat 8 and 9 that includes the mpeg audio input plugin. Red Hat shipped without support for mpeg audio due to concerns about patents. In able to easily be able to add mpeg decoding to a Red Hat install, these RPM's are built with the Red Hat spec file. The RPM's that are distributed by xmms.org are a bit different.

Source:

xmms-1.2.7-21.src.rpm

Binary packages:

xmms-1.2.7-21.i386.rpm
xmms-mpg123-1.2.7-21.i386.rpm (mpg123 plugin)
xmms-skins-1.2.7-21.i386.rpm (skin package)
xmms-devel-1.2.7-21.i386.rpm (devel package)

Håvard Kvålen <havardk@xmms.org>