The crew from TG Daily has found a bug in Microsoft Windows that seriously increases power consumption on Intel's Core Duo processor platform when you have an USB 2.0 device connected. They write the way that the current Intel ICH7-M Southbridge communicates with Microsoft's ACPI driver is the heart of this power drain issue.
TG Daily and Tom's Hardware Guide have been in communication with Intel representatives throughout this week about our findings described in this article. Late Friday, Microsoft acknowledged to TG Daily - via the hands of Intel - that they believe the problem our engineers observed to have been caused by a misbehaving driver included in Windows XP SP2 - specifically, the Advanced Configuration and Power Interface (ACPI) driver, which is part of the operating system's power management scheme for USB 2.0.
It's quite a big problem - it's not just a few minutes less battery life but more than an hour! According to benchmarks from TG Daily on a notebook with Intel's Core Duo T2300 this flaw decreased battery life with a shy 72 minutes.
Both Microsoft and Intel are working on a fix for this problem, but they don't promise anything. More details about this bug can be read over here.