I assume you are looking for necessary features first, and then price...?
Like Cubkid said... try IBM Thinkpads, a lot of them are really light and built to the highest quality you can imagine for a laptop.
They are a bit pricey, but it is for the quality and craftmanship, not just the features.
http://www.thinkpad.com
You can also try Fujistu Lifebooks, they are really light and small. The quality is pretty good, definitely better than Dell and Compaq stuff.
The smallest Lifebooks run on Crusoe CPUs, the same type of CPU used in those tiny Sony Vaio laptops.
http://webshop.fujitsupc.com/fpc/Eco...pgid=Notebooks