I own and use a 17" Powerbook daily. I would consider myself an audio professional, recording bands and music is more than half my income.
I <3 my powerbook very very much. OSX is STABLE. If you remember back to OS 7.5 or later, macs were very crash-prone, but not this thing. I've owned it about 7 months now, and I think it's crashed maybe twice.
As far as college plans go, I recommend you go out and get the MS Office for OSX (student edition) for $150. Now you have MS Word, and your english professor will be happy.
For the internet: Everything just works. There's no BS about it. No problems whatsoever so far. I replaced my quicktime player with realplayer, but that's just because apple wants you to pay for full screen (yeah right).
For Audio: I use Pro Tools, as most studios do. It runs like a champ on here, I'm in the middle of recording an album right now that is 40 gigs big already. It never crashes! I can't stress that enough.
You seem to want to fool around with garageband, I've messed with it a couple of times on here. It's basically a stripped down version of Pro Tools, but with ACID-like loop sequencing. My powerbook has 1 gig of ram, so garageband runs perfectly. You'll want a lot of ram if you want to do music recording.
If you just want to use an iBook to record demo stuff, you'll be more than happy with garage band. Go to radio shack, buy a mono to mono 1/4" to 1/8" cord, and plug your guitar or bass right into the audio in port on the iBook. The sound quality isn't going to be amazing by any means, but you'll hear a guitar or a bass. It won't sound horrible at all, definitely demo worthy.
If you have any other apple audio questions, just ask. I completely recommend any apple computer though, they haven't failed me yet.
