[Scotty doesn't know]

Most all of the songs on Guitar Hero are by a cover band of some sort, for which it is labeled 'made famous by' instead of 'as performed by' when it's the real deal. Some of the covers sound almost just like the real band, and others not so much. The only band I can think of right now that actually performed its own song was Primus, on Guitar Hero 2. There may be others that I'm just not remembering, too.

No, no. Nirvana did one..LOL. Just kidding. (I loved Nirvana)
The Primus song you mention is an awesome song. It was done specifically for Guitar Hero II. I will have to pop that GH I and GH II in and see what other ones say 'as performed by'. I think Shadows Fall-The Light That Blinds (after thinking about it) is one too.