The November 2008 - Service Pack 3 for Windows XP Embedded Optional Update is now available on the ECE for Microsoft® Windows® XP Embedded with Service Pack 2 and/or Feature Pack 2007.
Windows XP Embedded Service Pack 3 (SP3) is a roll-up of hot-fixes and security updates Microsoft has released since Service Pack 2 (SP2). It also includes select out-of-band releases, and a small number of new enhancements, which do not significantly change customers’ experience with the operating system. Windows XP Embedded SP3 provides a new baseline for customers deploying Windows XP Embedded. For customers with existing Windows XP Embedded installations, SP3 fills the gap in the updates they might have missed.
Please check this link on the ECE for more details:
November 2008 - Service Pack 3 for Windows XP Embedded Optional Update – Product Download
If you have questions on accessing the ECE, please email MS Mobile & Embedded Communications Feedback & Support, ECE@microsoft.com.