mp3 in centos 5

xmms works for me.

I add Dag Wieers rpmforge repository with:
rpm -Uhv http://apt.sw.be/packages/rpmforge-release/rpmforge-release-0.3.6-1.el5.rf.i386.rpm

Then:
yum install xmms xmms-skins xmms-mp3

There was a problem in that the doublesize option didn’t work correctly but this has been fixed with the latest update (1:1.2.10-14.el5.rf).

To enable mp3 in totem and rhythmbox (and for Sound Juicer CD ripping to mp3) you can do:
yum -y install gstreamer-plugins-bad
yum -y install gstreamer-plugins-ugly

These also come from rpmforge.