MIDI to WAV/MP3/OGG

Hi there, I'm new.

Could anyone suggest a free or open source tool to convert MIDI to WAV/MP3/OGG? Or explain how one might do this using the command line? I'm presently using Ubuntu GNU/Linux 6.06 and can't even play MIDI files, much less convert them. Neither Google nor Synaptic (Ubuntu's package manager) has suggested much.

A Debian package is preferred but not essential. Thanks in advance.