I buy a new laptop every 18 months, fairly religiously. This is not because I want the latest gadgets, but because that usually is their optimal running time for someone who uses their as often and hard as I do.
This has been true for Dell, HP, Compaq and Toshiba laptops for me. I am on my fourth Dell. Not because they are bad, but because they've been reliable and have good customer service (after you suffer through the long obligatory troubleshooting call).
My next laptop will be a Mac (Vista Avoidance), so we'll see how it goes.
I feel its necessary to say this because people who have always had desktops are asking me which laptop to buy.
Laptops take a massively higher number of jolts than your desktop computer could ever dream of. They are rugged and strong. And their reliability has improved dramatically. But you won't be using it for five years.
Also, you probably aren't like me, where you are traveling 3 weeks out of four and are only using your laptop 10 hours a day. I have no desktop. My laptop is my only machine.
I also wanted to say ... I really appreciate the dialog box that appeared for me today on my Dell D820. I actually think the battery is still in warranty, but the fact that the dialog came up, very clearly stated the problem, AND gave me a single-click opportunity to cure! That is wonderful!
Thanks Dell! Good on ya!