Use Hibernate and Standby to Conserve Batteries

Fast User Switching can be turned-on with Windows XP Professional only when your
computer is not part of a domain.
Power Options in Control Panel lets you adjust any power management option that your
computer's unique hardware configuration supports. These options vary widely from
computer to computer. Power Options automatically detects what is available on your
computer and shows you only the options that you can control.
ACPI-If you are not sure whether your computer is ACPI-compliant, check your
manufacturer's documentation. During Windows Setup, ACPI is installed only if all
components present during Setup support power management.
The Hibernate function in Windows XP Professional can make the batteries in your
laptop computer last longer.
Windows XP supports the industry standard power management technology known as the
Advanced Configuration and Power Interface (ACPI), which enables the operating system to
control power to your computer and peripheral devices. The power management features in
Windows XP include Hibernate and Standby. Hibernate saves an image of your desktop with
all open files and documents, and then it powers down your computer. When you turn on
power, your files and documents are open on your desktop exactly as you left them.
Standby reduces the power consumption of your computer by cutting power to hardware
components you are not using. Standby can cut power to peripheral devices, your monitor,
even your hard drive, but maintains power to your computer's memory so you don't lose
your work.