to answer your question.. it's not done, the boards aren't designed to be upgraded in such a manner, and the cost of new technologies makes it not cost effective..
if you have one where the cpu is toasted, then it can be done, but not easily..
Well I have two laptops. One's a dell m1330. An amazing machine. 2.4 duo core, 4 gigs of ram, dedicated video etc etc etc.
Fucking thing needs its 3rd motherboard. My warranty is out. Dell wants 500 bucks. So, I'm not going to fix it yet. Later I'll get it fixed and sell it, hopefully make a few hundred off it.
I also have a gateway, but it's less spectatular. 1.6 duo core, 1 gig of ram. It works fine, it's just not what I'm used to.