Through our extensive collaborative research, we can report that an Advanced Configuration and Power Interface (ACPI) driver in Windows XP Service Pack 2 is the sole cause of the unusually high power drainage observed by all three teams. Today, Microsoft confirmed to TG Daily that it is developing a new patch to fix this particular driver bug, whose nature is somewhat different of those those addressed by earlier Microsoft Knowledgebase postings.
It’s good to know that this is being worked on, but really, if it was an ACPI driver issue you would think they’d find out sooner. Check out the article at TG Daily.