What is the best developer laptop on the planet, and why?

HP I’ve been discussing various aspects of the developer world with Andrew Kass lately and as you know I am not short on opinion.  So I thought I would ask you a couple of questions.  I know a lot of you are either developers, used to be developers, or know and have to deal with developers.  Grin.

What is the best laptop for a developer, and why?  

Sounds like a simple enough question but there are a lot of variables.  And if you were going to buy a machine today, what would it be? 

What operating system would you run?  What would the toolset look like?