Well... I got a pretty battery hungry laptop...
Dell Inspiron 8500, P4 2.4 M, 15.4 inch widescreen SVGA+ LCD, 64 MB 4200 Go. (Full Specs in my sig)
It is around 4 months old, and still manages to give me over 3 hrs of battery life.
If you are looking for battery life primarily... get a Pentium M, preferably with 2 batteries.