Both Dad and Becky are in the market for a laptop so I thought I would write up my guidelines for buying a laptop.
Buy the extra Battery!
For Dells, it is called the Media Bay battery. This is the most important item to buy. It allows you to swap out your CD drive with an extra battery. You know how often I use my CD drive? Maybe once a month. You know how often I use the extra battery? Everytime I go to the coffee shop. It basically allows you to survive for a decent amount of time without carrying around the power brick. No more worries about finding a seat by an outlet.
Memory is More Important than CPU
Get 512MB minimum. Laptop disks are SLOW and the CPU slows down every time you unplug so it’s not like you are using all 2Ghz anyhow. Get the extra memory because you do not want to page to a 4200rpm drive…
Disk Space is not that Important
Drives are so big these days that the only way you can fill them up is with media: MP3, video, etc. If you are not going to mess with video and your CD collection numbers in the tens, you don’t need to upgrade the disk.
Everything in Moderation
Unless you have special needs (like Bob, zing! 
you should avoid the biggest and smallest models in a vendor’s lines. They usually require serious drawbacks - the largest ones are not terribly portable and the smallest ones are hard to type on and have small screens. I had a Dell 800 and it was simply too big. The Dell 500 and 600 lines are sized much better for normal people.
Finally, why do laptop vendors continue to include parallel and serial ports on laptops but not Firewire? Those two ports alone take like 50% of the port space on the back of my Latitude. Put some more air holes there instead so my lap is not on fire!