As I see it, the main advantage of taking notes on a laptop is that you can search them quickly on the computer. It's not possible to do that with handwritten notes, and I can't imagine transcribing notes after taking them by hand (ahh how nice it was to have a secretary). Anyhow, I'll probably be doing both, typing notes into the laptop, and also taking notes by hand that I can reference.
With regards to using a Mac, I agree with Lepium. I don't know about other schools, but I know that Darden has specific requirements for integrating laptops with their system at school. For example, the required XP Pro or Vista Business - XP & Vista Home do not have the required security functionality and cannot be configured for use on their network. I can only speculate, but I don't believe that Macs running parallels could be so configured either. I think Bootcamp (as I understand it) might work because it basically boots up a copy of XP and you can utilize Pro. However, as Lepium said, why pay more, just so you can boot to Windows?
Another thing about Macs is that they get really really hot, uncomfortably so. I guess there are different opinions about this, but it seems that most people attribute this flaw to designing for looks over functionality. Whatever the reason, the heat is really annoying. The fans in Macs are also really loud - according to a friend loud enough to be very noticeable in a classroom or especially in a library. Some of the better designed business notebooks run 30-40 degrees cooler than Macs, and have whisper quiet fans that rarely come on.
I've voted with my pocketbook and selected a nice Lenovo. I was wondering what people view as the strengths of Macs in a business setting. Other than the looks (which are a matter of personal taste and completely meaningless to me), why would someone want the aggravation of trying to work with a Mac when everything is designed to work with Windows? Not a rhetorical question, I'd actually like to understand.