The problem is that in real the gfx chips technology hasn't as much improved as the desktop market might make you believe because if you take a look at the insane power consumption, the large cooling devices and how big the cards became, that's nothing i would call a real advancement. As you can't cheat this way in laptops it gets more obvious how far they really progressed, still a lot but simply not this much. Nevertheless the latest mobile chips from both nVIDIA and ATI are more powerful than each iteration before.