For laptops, I usually recommend Macbook Pros, Dell Inspirons or Macbooks. (Usually in about that order.) Edit: Lenovo/IBM Thinkpads are also good Windows business-class machines, although unless you are an Excel number-cruncher I usually don't recommend them.)
If you want a wicked awesome computer, get the Macbook Pro. A medium-spec Macbook Pro at $2500 (with a lifespan of like five years*) is basically the same price as two cheap (about $1000) Windows laptops each lasting two-three years.
After that, my second recommendation is usually split between Dell Inspirons and Macbooks, depending on your usage. I've owned an Inspiron for almost two years now, and it's still going strong [with everything except CAD].
If you're planning on doing a LOT of intense CAD work, I might lean towards the Inspiron with upgraded RAM and video card running XP Pro. Although you can use Boot Camp and install XP Pro on the Macbook, and do the same thing if you want to.
* Team 228 has always owned more Macs than PCs. We used several circa-1999 iMacs up until about 2005 as some of our main computers; and we're still currently using a circa 2003-iMac as one of our primary computers.