This is for a FILM SCHOOL. I bet very little of your time will actually be in FCE or FCP.
99% of your time will be writing essays, checking email, reading references, watching DVDs and clips for your course work, doing research on the web.
I strongly suggest getting a laptop.
You will be moving about a lot, so I suggest a macbook for portablity. You'll be able to do your work / research / writing in both college or town or home.
If the film school is any good, there'll be a huge amount of theory that you have to read, watch and understand. You'll be learning about the films of Bunuel, Fassbinder, Einstein, Barney, Kurosawara and many other obscure but influential filmmakers.
A macbook will blow almost any PPC out of the water as far as FC goes, especially any PPC that you can get for the same price. Especially a C2D Macbook if you can get one.
I suggest waiting till NAB, see what happens there, then getting one through the refurb shop or the educational discount or the ADC discount, or even through your film school (they might have very good deals, but you may need to access the apple education store from a computer on their network).
Furthermore, while you are actually in FC, very little of what you do will actually tax the laptop or G5 or whatever you do. Film school is not about flashy special effects. It's about learning shot composition, correct lighting, edit placement, story structure, and many other things.
Furthermorex2, you may not need a huge hard drive. I would bet that there is a strict maximum length on student projects. Your teacher doesn't want to be watching hours of dreck - it's possible your films will have a maximum length of 5 minutes or less. Quality not quantity is what counts, and a good 4 minute film can easily take a month to do.
Furthermorex3 later as your finances warrant, you can add external LCD for extra space in your dorm room, and an external HD for storing your projects on. When you need to do some heavy lifting or effects work (which will be suprisingly rare) you can take that external HD and plug it into one of the lab beasts. Your C2D macbook may actually be better than most of the lab computers, as they don't get upgraded all that often.
A 15'' MBP would certainly be 'better' but considering your finances, a discounted C2D MB is my strongest recommendation to you. For college it's critical that it stay working at all times, so I strongly suggest 3 year AppleCare (isn't this free with some educational purchases?) and theft insurance.
You definitely don't need to pay full price for FC (P or E) there will be large discounts at your school, or er, ask a fellow student what bittorrent means.
I'm typing out all this not just for you but for all these other people who think films / film school are about being flashy or having the best equipment. It's not. It's about knowing your stuff, the theory, the lighting, the composition, listening to your gut, and learning how to use well what you have on that day.