!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!PLEASE SEED THIS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Source for Service Pack 4:

Using Goldfish_92's Windows XP Service Pack 3 ISO I slipstreamed it with the unofficial Windows XP Service Pack 4.

Windows XP Unofficial SP4 ENU is a cumulative update rollup for Windows XP (x86) English. It can be applied to a live Windows XP system which has SP1, at minimum, installed or it can be slipstreamed (integrated) in any Windows XP installation media.

It includes updates for most Windows XP components, including MCE and Tablet PC. Request-only hotfixes have been included. Currently, Microsoft .NET Frameworks 4.0, 3.5, 1.1 and 1.0 (Tablet PC only) are included in the Windows XP SP4 package. In addition, all post-eol updates for .NET Framework 1.1, 3.5 and 4.0 until January 2016 have been included. The .NET 1.x, 3.5 versions are automatically installed/updated in live installations. Only Microsoft .NET Framework 3.5 is enabled by default in integrated installation. Microsoft .NET Framework 1.1 will be always installed if Media Center Edition is present.

If you download the WindowsXP-USP4-v3.1b-x86-ENU.exe you can also scan Windows Update for POSReady updates, because the POSReady trick has been included.

Windows XP SP4 security enhancements: Windows XP SP4 includes registry updates to enhance security. I want to thank Stefan Kanthak, a security expert who has kindly given me the necessary information. These security enhancements address issues not fixed by Microsoft updates.
This is an example of security vulnerabilities fixed by Stefan's registry updates: http://seclists.org/fulldisclosure/2013/Oct/151