Actually doomey!, there is no Guitar Hero for the 360.
There is Guitar Hero 2, but not Guitar Hero.
As for the original question - if you are wondering about the 1st Guitar Hero for the Playstation 2 then you can actually play the game with a normal PS2 controller and not have to worry about buying the additional 'guitar control pad'.
You don't really need to play the guitar to play the game, you basically need a sense of rhythm. Also if you've heard of the songs then it'll be easier to play. I'm a guitarist and my friend is a drummer, we play just as good as each other.