Here is a link to the official cmpatibility chart for Guitar Hero and Rock Band software and the games they will work with.  It also breaks it down by system.  The XBox 360 seems to have the best when it comes to what hardware will work with what games, but the Wii breakdown isn't too bad.

To fully answer the question, the Band Hero hardware (which is equivalent to the GH5 hardware - that's why you don't see it on the list) will work with Rock Band 2, but not original Rock Band, unfortunately.

JB