Buying a laptop (educate me)

[Strichev]

In a few months (yes, I tend to plan such "investments rather carefully) I'm going to find myself in need of a laptop. Since buying a laptop and building a desktop are vastly dissimilar, I thought I might just as well ask you people about them. Laptops that is.

Share your experience and wisdom. Be it a plastic casing compared to an aluminium one, various sizes, SSDs, processors, firms...everything...post it. I need to acquire a general feeling for the things the market has to offer, for there is hardly anything worse than running into a store or a web-site and blindly pick the first thing one sees.