Is he going to be composing music because that's what he's majoring in, or will he be doing it purely as a hobby?
I have a child who dates a music major, and I know the software that they use at her conservatory is MAC-based. She had to buy a MAC, and I think she actually purchased it through her program, and it came with some specific software pre-installed.
Not a hobby. Music Composition major, and our child has already composed several pieces (using our PC music software, as well as composing music by long hand).