Windows XP Service Pack 3 (SP3) Available for Download from Windows Update

Finally, Microsoft has made Windows Service Pack 3 (SP3) available for download via Windows Update (Web).

Service Pack 3 will contain all previously released Windows XP updates, including security updates, out-of-band releases, and hotfixes. SP3 will also feature four Vista features.

• Network Access Protection (NAP) is a policy enforcement platform meant for enterprise use that blocks systems attempting to access a network until they meet whatever security criteria the corporation has in place.
  "Black Hole" Router Detection helps detect and protect end users from a router that drops packets without returning the specified Internet Control Message Protocol response.


• Microsoft Kernel Cryptographic Module incorporates cryptographic algorithms in a single module other kernel mode drivers are capable of hooking into and accessing.


• The new Product Activation module allows users to install XP without entering a product key at installation.
  Article from ars technica

http://arstechnica.com/news.ars/post/20080429-microsoft-releases-the-long-anticipated-windows-xp-sp3.html

Windows XP Service Pack 3 Overview (in pdf)
http://www.microsoft.com/downloads/details.aspx?FamilyID=68c48dad-bc34-40be-8d85-6bb4f56f5110&displaylang=en#filelist