This application isn’t anything more than an install packet that gathers all the Windows updates published since it first came out.
The Service Packs don’t just include updates, but also security patches and other improvements that were published as updates.
Among the most significant improvements in the Windows XP Service Pack 3 are:
-The centralized panel for administration Microsoft Management Console (MMC).
-MSXML6, which improves compatibility with the W3C recommendations about XML
-Windows Installer 3.1 v2, a Windows Installer update needed to be able to install certain applications.