In that case I would advise you to get him Adobe Audition or Cubase or Logic, they all more or less work the same, so if he gets the hang of one of them it shouldn't be to difficult to switch to one of the other ones.
A good begginer Mic to get him would be anoything Behringer really....my first mic was a B1 (
http://turnkey.co.uk/product.php?itemid=261). Since he's only doing it as a hobby he wouldn't really need a top of the range mic, anything under £150 should be alright.
Then hes gonna need a mixer to plug the mic into, again imo Behringer is the best for good quality cheap mixers,
http://turnkey.co.uk/product.php?itemid=352 one of my mates just bought this mixer....cheap and it does the job.
Your also gonna need some audio wires to connect the mixer to the Pc, when you buy everything ask someone that works there and they should be able to help you out. Your gonna need a XLR cable for the mic aswell (Cables shouldn't be more then £30-40) and a stand for the Mic (£20) and a pop shiled (£5)
You might want to get him some Monitors aswell depending on what kinda speakers he's got already. Then again imo Monitors aren't really needed if your only doing it as a hobby
All in all your gonna be spending around £200-£250 getting everything, thats not including the Software though...I get my copies from a....friend...
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Hope that helps
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Edit - Just realised your from the states so everything should be cheaper I'm guessing lol