Had a desktop all through uni, had no problems. If I were to go back again I'd still be happy with a desktop (though I own a laptop for work now) but I'd probably look to set up a proper home network with dns etc, make getting at my home stuff from uni a bit easier.
That said, when you graduate from uni a laptop may be handy - you can take it to interviews to demonstrate your work. Showing is much better than telling!
(Alternately you can make sure your work is easily viewable online, assuming the interview location has some machine to access it - a lot depends on your field I guess! No idea what civil engineers would need to demo their awesomeness)