From what I've seen so far: people who've tried to switch to using their laptops for note-taking go back to what they are comfortable with before optom school started.
My laptop has a bunch of powerpoints on it, and study sheets, and papers, and all that jazz, but we get hard copy course packs and I have my handwritten notes on those.
If your laptop mostly sits on your desk @ home then (if I were a betting woman, which I am 🙂) I'd say you probably won't use it during class too much.
So, if you really need a new computer, I'd say go with a laptop, but that's just me. Sometimes you just need to get away from your home... you can't really take a desktop with you to study in some corner of the library. 🙂