PC Magazine has posted a series of tips to get the most battery life when using your notebook PC.  As summer travel season progresses, This is timely advice.  Of particular note is a freeware utility for Windows XP called SparkleXP that makes configuring your notebook for maximum battery life easier.  A beta version for Vista is also available.    According to the SparkleXP web site:

SparkleXP is an application designed to tweak Windows XP and improve its performance,
it helps freeing up computer resources resulting in a faster and responsive computer.
This tool creates a second Hardware Profile and a correlative new User to get a lightweight desktop. You can choose to boot into your regular or SparkleXP configuration at startup.