Well, a home recording studio needs a computer. What type of computer is your friend looking to use? A Wintel machine or a Mac? I would recommend a Mac if this person has no preference, but if by chance she is a PC user and won't warm up to switching, then she would need a decent PC computer.
Roughly how much is your friend wanting to spend? A home recording studio costs money, no doubt about it. If she's just doing this as a hobby, she might want to just get a MIDI controller for her computer and use the inputs that are on the current computer for audio. She could also mixdown to CD, which would require software.
It's been a while since I've researched any of the music production software packages out there. I myself have been wanting to get back into doing that, but time is not on my side at the moment.
Anyhoo, I think we need to have some more information regarding a budget, computing platform of choice, instrumnets of choice, etc. That would help narrow the search.
