Over 390 different artists have tracks available and users can purchase tracks within the game.

In the two years from its launch, over 60m tracks have been downloaded by Rock Band gamers. Downloads are the next booming revenue stream for music-based games after the market for peripherals such as guitar controllers.

MTV Games has suggested the number of downloadable tracks will mushroom when the Rock Band Network goes live next year. It was originally planned for release this year, but ...