Instructions
Reference a Rock Band/Guitar Hero compatibility chart. (See Resource) These charts comprehensively list which peripherals from these two popular series are compatible with each other. Begin by locating your gaming system, Xbox 360, Playstation 3 or Nintendo Wii.
Identify your guitar model. Some charts from third-party sites like Joystiq provide pictures alongside the versions of guitars for easy identification, but they are often not as thorough as Rock Band's official site. The distinct shapes and colors, in addition to knowing which version of the game you own, should make this quick.
Compare your guitar to the compatibility matrix. As you can see from the charts, Rock Band guitars are completely incompatible with Guitar Hero 3 (GH3) and worked for only Xbox 360 on the subsequent follow-up "Guitar Hero: Aerosmith." With the release of "Guitar Hero: World Tour," the integration between games was finally built in, and to date (January 2011), all guitars between the franchises are compatible with their concurrent counterpart.