This Alesis model is fine for fairly basic stuff, worth getting if he's semi-serious.
Also very popular are Roland's Dr. Drum products (
http://www.rolandus.com/products/sub...d=2&subcatid=0)
Best option is to use software though. If he uses Steinberg's Cubase or most of the Cakewalk products he should already have options to play around with. Another popular one is Fruity Loops which is intended for electronic-type music but you can also get some sweet rock/metal drum settings out of it (with enough patience, that is.)
Hope this helps.