I started college with a desktop only. At the end of September I ordered an old IBM laptop off of eBay. (iBook is on the way)
College is a time when you experiance an entirely new level of freedom that you could have never even considered possible in high school. Beleive me, you will want a laptop. There have been so many times when I have spent entire days at the library, or at a friends apartment, etc. that I have been so glad to have a laptop. The fact that you can have your computer with you, ready whenever you need it becomes more than just a cool thought, it becomes an integral part of your live that you literally can't function (socially or acedemically) without. I know this sounds like an overstatment, but I know there are plenty of people out there who know exactly what I mean.
Computer labs....they are a joke....if you need to use a computer while you are in the "acedemic" area of the campus, your better off walking home than waiting in line.... This is not a problem if you have a laptop, especially now that most schools are at least partially wireless (my school has the library, SUB, and about half of the acedemic buildings set up...more on the way)
Heck, even if you never take your laptop out of your room, its so nice to be able to relax in bed while surfing/chatting. I am so in love with wireless that I am getting a 802.11 base for my dorm room!
As for your concerns over the abilities of the hardware in laptops....the sacrifices you have to make for portability are not as bad as they used to be....if you want to see for yourself, just stop by an Apple Store or Comp USA and try out the iBooks and PB's...you'll be impressed how much something an inch thick can do!

Just for an example, my roomate is a Communication Design major (anything and everything graphical), and he is getting a 15" PB...like basically everyone else in the major....(2nd largest CD program in the country).
Personally, if I were you, I'd wait for a little bit....the G5 Power Books should be out by summer, and are sure to give mroe than enough power to put your future-proofing fears to rest.
