Well this is the reason people hate laptops even though mines better then half their desktops.
A laptop will cost you 10% less to build as to buy one.
Now desktop is different.
A desktop could be built for half the cost of buying one.
Also graphic cards are the hardest part to change in a laptop unless you bought quality like me.
But if you decide to buy I would recommend Alienware like I have and abuse the graphic amplifier.
This alllows you to have a tv on a desktop gpu, a monitor off a desktop gpu, and then have a third screen with the laptop gpu too if you need yet another screen.
Also has the benefit of it will outlast your desktop because no matter the gpu they come out with your laptop can use the best.
Only time it would become irrelevant would be when the ram and CPU limit is reached which takes 8-10 years compared to a gpu that is inefficient after 1-2 years.
That's why I'm streaming LoLz right now and why I have bought 9300 IP on two accounts so far. Because I don't play it. Makes perfect sense ~ Karmic Dragon