Buying a laptop?

There are a lot of things to consider when buying a laptop / notebook computer. So I was reading an article on building your own laptop at Tom's hardware. I realized that although the points he mentioned were important things to consider when building a laptop from scratch (did you know you could do that?) - every point was also a good primer on what features to consider when buying a pre-made retail laptop as well. For example, how big should your screen be, why some CPUs are better than others (for power management), etc. For other takes on what to look for when buying a laptop, see PC World's article