System Memory

Since most laptops today come with at least 2GB of RAM--and since that's good for most purposes, especially if you're going the Linux-only route--this factor shouldn't be too big an issue. Of course, if you're planning to dual-boot or to go with a 64-bit distro, you'll want to get more.

Optical Drive

This shouldn't be a big factor to think about unless you're planning to watch Blu-ray movies, in which case you'll need a Blu-ray optical drive that can read and write DVDs. You'll also have to get some extra software for decryption.

Weight, Screen, Hard Drive, Battery, Keyboard, Software