Desktop Update Overview (Windows Embedded Standard 2009)
Desktop updates are updates that are released by Microsoft for Windows XP Professional. Because Windows Embedded Standard is a componentized version of the Windows XP Professional, Windows updates can run on Windows Embedded Standard run-time images that include the required dependencies.
Desktop updates are used to apply incremental updates to a run-time image. Combined with suitable testing, the incremental application of desktop updates reduces the size of the update package and the cost of deploying them.