Technically, I don't NEED a laptop. But I want one. I go to friends alot, and taking turns on the computer is a major drag. And long road trips. We drive to California every year from Washington. Not many things to do when you hate your siblings with a fury.
What games do you plan to play? And laptops are not the most reliable thing on this planet, either. It depends on thebrand.
Here are the two ends of the spectrum:
Games like Crysis: Probably the Intel i series, with a nvidia 240gt. 2000 plus in a laptop. about, 1200 in a desktop Im guessing.
Valve Games: Computer with a Pentium processor should be good, and Nvidia geforce 8 series. about 800 in a laptop, 500 in a desktop.
I mean, im just estimating there. Crysis you need a batstuff insane computer to run maxed out on.
The Valve games need a decent computer pretty much.