Halo and Guitar Hero fans are in for a treat today, with the release of the Halo theme Mjolnir Mix as a free download on Xbox LIVE Marketplace.

Once downloaded Guitar Hero III players will be able to rock out to the iconic theme tune by Martin O'Donnell & Michael Salvatori, with guitars performed by Steve Vai.

This is already the second free download for Guitar Hero III, the first giving players the ability to play the game's three boss battles as standard songs apart from within the career mode.

Guitar Hero III is released for Xbox 360, PS3, Wii and PS2 across the UK on November 23.