Desktop vs. Laptop
I've used a laptop throughout collegenow on a mastersand its been really useful for a few reasons:
1. Portability, you can go to the library, the coffee shop, a friend's dorm room, class, the mall, the union, etc. This gives you some flexibility if say your printer dies, your local internet connection dies, your roomate has decided to take up guitar and can't get through the first five bars of 'Blackbird' without screwing up, etc. (Thanks Chris!)
And now with wireless you can go without cables.
2. Space-savings, dorms are tiny, the desks miniscule and quite simply a desktop and tower use a lot of space.
3. Performance, Apple's laptops are very powerful for most things. Futhermore, I'm not sure what your major is, but I can't imagine anyone but an architecture student, graphics design pro, etc. using the power of a G5.
I have my PB and it works rediculously well for me, being able to take notes in class, access my mail, complete research using wireless points, etc. It's awesome.