Windows XP Service Pack 3 (SP3) includes previously released Windows XP updates, including security updates and hotfixes. 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.
Microsoft is not adding significant Windows Vista functionality to Windows XP through SP3. However, SP3 does include Network Access Protection (NAP) to help organizations that use Windows XP to take advantage of new features in the Windows Server® 2008 operating system. Further, Windows XP SP3 does not include Windows Internet Explorer 7.

Previously Released Functionality

The following functionality is already available for Windows XP in stand-alone updates. System administrators must choose to install each of these updates, however. Windows XP SP3 includes them by default.
MMC 3.0,MSXML6,Microsoft Windows Installer 3.1 v2 (3.1.4000.2435),Background Intelligent Transfer Service (BITS) 2.5,IPsec Simple Policy Update for Windows Server 2003 and Windows XP,Digital Identity Management Service (DIMS),Peer Name Resolution Protocol (PNRP) 2.1,Wi-Fi Protected Access 2 (WPA2)

New and Enhanced Functionality

Table 2 describes some of the more significant changes in Windows XP SP3. With few exceptions, Microsoft is not adding Windows Vista features to Windows XP through SP3. As noted earlier, one exception is the addition of NAP to Windows XP to help organizations running Windows XP to take advantage of new features in Windows Server 2008.
“Black Hole” Router Detection,Network Access Protection (NAP),Descriptive Security Options User Interface,Enhanced security for Administrator and Service policy entries,Microsoft Kernel Mode Cryptographic Module,Windows Product Activation

 Note: You do not need to install Windows XP SP2 before Service Pack 3.

Download

For Home Users click

 www.windowsupdate.com

For Network Installation and Deployment Solution

windowsxp-kb936929-sp3-x86-enu.exe

 

For More Details

Windows XP Service Pack 3 Network Installation Package for IT Professionals and Developers