IBM makes ROCK SOLID laptops. Seriously solid stuff.
The thinkpad T-series laptops are their ultraportable line, but they're expensive. I'm on a T20 now (10 model series old, they're up to T30s now) and its easily carried around in one hand.
The problem a lot of people have, is they're not super-customizable like Dell laptops. If you need to customize your laptop, Dell is probably the way to go.