Laptops are great. The most obvious beinifits are that its compact and easy to travel with.
I played on them for about two years while away at school. I still do at times, and with AH2 out I had to buy another one. I ended up with Alienwares Area 51 laptop. Among all its perks, the Geforce 256mb 6800 Ultra video card.
Its extreme over kill in my opinion as far as a laptop goes. For the money I put into buying that thing, I could have build another desktop that is capable of running NASA.
Also, the screens, no matter how much the manufacturers will boast about how large and great they are, are still small. When I play on my desktop,with a 24inch screen, its like a different game all together. (which I built for one thing in mind, gaming)
In the end, its all what you want to pay, and how much your willing to sacrifice by going with a laptop. With the new laptops like the Area 51, you wont sacrifice alot, but it still has its drawbacks from being a laptop as aposed to a desktop, and being used for gaming. How much gaming you do might offset that.
My recomendation....If you've got the space, and really dont need a laptop, go with a desktop. You can build your own now very easily, one thats suited for gaming and will perform well with all tasks today for a realativly cheaper cost.