If your Windows XP laptop battery discharges sooner than expected, don't blame on the notebook manufacturer - the real culprit could be Microsoft Windows XP SP2.A Windows XP SP2 USB bug causes a notebook battery to drain faster than usual when there is a device connected to the computer's USB port.
The Notebook battery drain flaw lies in the ACPI (Advanced Configuration and Power Interface) driver of Windows XP SP 2 that is part of Windows XP power management scheme for USB 2.0. Read Microsoft comments:
While there is a noticeable impact on battery life when USB 2.0 devices are plugged into some specific models of laptop computers, these systems are still fully functional and newer systems have significantly longer battery life than their predecessors, whether a USB 2.0 device is plugged in or notThough there exists a registry key fix for the USB bug, it is not meant for general customer user. Microsoft confirms that the USB flaw in Windows XP Service Pack 2 does not have an easy fix
Source: Elizabeth Montalbano @ Info World | Computer World