Again, it really all depends on how much you want to spend. Also wether you plan on using the laptop or a desktop more. Of course among many other factors.
Do you have a monitor for a desktop or would you have to purchase another?
One drawback about buying a laptop is that you cannot change the graphics card on almost all systems (except some offerings from Dell, Alienware, and I think Voodoo).
Personally I would go with a desktop. I too had the same train of thought of you when I went off to college. I purchased this huge multimedia laptop thinking I would game with it for endless hours. Believe you me, I gamed, but not even a year after I owned it the graphics card went obsolete, sure enough two years down the road and it was beyond obsolete...I purchased it for $2200 originally.
Do you know how to build a desktop or would you pay someone else?