Dj_bridges - If you are still on KDE3, SoundKonverter will convert *m4a to *.mp3 or many other formats. Set for Lossy, and High, or Very High.
> If you are on KDE4, it seems not to have SoundKonverter, but does have TranscoderAudioEdition. I just put that into my 2009.2 / KDE4 - running in Virtual Box. It only has *.mp3, *.ogg, and AAC as conversion options, but did convert an *.m4a file to *.mp3.