things that can render a laptop unusable:
- poor display, keyboard, or wireless card; excess fan noise or heat.
nice to have: fast Core 2 Duo, minimum 2G RAM, if you're doing lots of compiles, spidering (DOM tree extraction), database indexing, anyting that pegs CPU's for more than a couple minutes.
like everybody else, my first choices would be macbook or Macbook pro/ Vmware fusion/ Windows XP and ubuntu, or thinkpad with XP/grub/ubuntu (i don't think you can buy them with XP pre-loaded anymore). Toshiba, Dell, HP still sell XP pre-loaded (the "downgrade option") Macbook is only model Toshiba satellites aren't bad, mine's been reliable for 3 years. Read the amazon reviews.