It's replaced my laptop for when I'm not going anywhere on long trips, or visits to cousin's house (I use to bring my laptop there to chat on IM and stuff when we're not playing videogames). So for IM, email, purposes I use bring my n800 now.

And as for the desktop thing. You could connect a laptop with an external keyboard, mouse, and external monitor. And as for power problems you could just get an expensive laptop. But after that point, you better really be using your laptop for everything. Since the money you spent on that could've been justified by a desktop and a not so powerful laptop.

But yes, your right. Desktops will never be replaced. Because of no expandability (the only thing you can change in a laptop is RAM if they even let you do that) and power.