Windows XP build 2600.5512

Windows XP build 2600.5512 is the official RTM build of Windows XP Service Pack 3. It was released to manufacturing on 21 April 2008 and was made available for download via Windows Update and the Microsoft Download Center on 6 May 2008. 2 months later however, Microsoft began pushing Windows XP Service Pack 3 to users of the Automatic Updates service on 10 July 2008.

New features and changes
References:
 * Includes 9 features by default that were already available in previous updates such as MMC 3.0, MSXML6, Windows Installer 3.1 v2, Background Intelligent Transfer Service 2.5, IPSec Simple Policy Update, Digital Identity Management Service, Peer Name Resolution Protocol 2.1, Remote Desktop Protocol 6.1 and WPA2.
 * Improvements to Black Hole Router Detection.
 * Adds support for Network Access Protection (NAP) which was backported from Windows Vista and Windows Server 2008.
 * Adds support for CredSSP Security Service Provider.
 * Adds Descriptive Security Options User Interface to the Security Options Control Panel applet to provide more information on Security settings.
 * Enhances security for Administrator and Service policy entries.
 * Microsoft Cryptographic Module adds support for SHA2 hashing algorithms.
 * Minor changes to Windows Product Activation in Windows XP Service Pack 3- Users can now complete OS installation without providing a product key and the OS will instead prompt the user for a product key later to complete activation.