New computer

So I'm thinking about getting a laptop, and this overclock thing is confusing me. How long will I actually be able to have the computer running at overspeed? Laptops that I've owned in past have always had heat problems (at normal speed), but it's been a while since I've owned a laptop.

Also, if I get a dedicated video card in the laptop, will intel's next CPUs have that much of an improvement over today's? I've read that the main improvement on them was integrated GPU speed.

I wouldnt overclock a lappy if I were you