KPlayer is a decent music player and a front-end for MPlayer.
KPlayer is available from the Packman software repository. This page should not be needed.
It's not pretty, but it gets the job done. MP3's work in KPlayer as soon as you build it.
Exract the tar.bz2 to a new folder.
Open a konsole in the new folder and type this:
make -f Makefile.dist && ./configure && make && sudo make install