'The Quest for Red Diamond' by nitro2k01. I think this is included on NitroTracker sample files, an XM music tracker for the Nintendo DS. (Hence, Nitro.) Anyway, the tune’s extremely catchy. He deserves more exposure!
EDIT (2014): Almost zero copy of the audio remains on the internets. even YouTube copies are broken. The above video is incomplete. Please wait while I render the .xm into an .mp3 (Though it won’t be perfect.)