Guitar Hero -
Absolutely NO translation whatsoever. The only remote help is stretching your pinky finger doing the Blue and Orange notes (or whatever the highest registers are on the Guitar).
Rock Band:
Drums actually translate very well. Drumming is all about rhytmn, and all of the songs help you. I play drums rather weakly in real life. However, after getting Rock Band, and playing Hard and Expert, I do believe it translates very well - as you can learn various beats, timing, and all the other misc. skills in drumming. The weakness is how the drums are positioned - as a non-electronic set is setup alot differently. However, it translates VERY well on an electronic drum set.
Rock Band:
Vocals "seem" to help out if you are working on expanding your vocal range, and staying on pitch. Im not a real-life singer, but I do think it helps a little bit.
So:
Guitar: Useless
Drums: Very useful
Vocals: Somewhat useful
Back from the dead, I'm afraid.
