Ben Fritz of Variety writes: "On the earnings call, Publishing President Mike Griffith said Activision has sold over five million song downloads for "Guitar Hero 3" on Xbox Live since the game launched. Recall that "Rock Band" has sold 2.5 million.
Of course, given that EA/MTV have sold 1.5 million copies of "Rock Band" in the U.S., compared to 6.5 million for "Guitar Hero 3," it appears that on a per capita basis, it's advantage: "Rock Band."
(One caveat: the vast majority of "Rock Band" units were for PS3 and 360, while many copies of "Guitar Hero III" were PS2 and Wii, which don't offer downloadable content. And Activision didn't include PS3 stats, for whatever reason. It's not clear how close the margin is just in terms of 360 owners.)"