Desktop all the way, you will get way better specification's for your money. And while you can go anywhere with a laptop you have to worry about the battries and not leaving it on the bus etc LOL.
Plus with a Desktop you can easily upgrade it yourself when you get a bit more money and make it even better.
It depends on what you want to do, if you want to play the latest games, go for desktop, but if you move around a lot, a laptop. It's not practical carrying a desktop around.