As many of you know Microsoft ended Windows XP support last April. Using a simple registry trick you apparently can still get updates for Windows XP. The trick works because Microsoft still supports and offers updates for Windows Embedded PoSReady 2009, which is an OS based on the XP kernel, until 2019. So you can trick Windows Update into thinking that you are actually running Windows Embedded PoSReady 2009 and continue to receive updates.
So to get your updates back on Windows XP you need to create a registry key called “HKLM\SYSTEM\WPA\PosReady” and there create a Dword called “Installed” with a value set to 1. You can do this manually using regedit, or create a .reg file using notepad and paste in the following:
Windows Registry Editor Version 5.00
Then you can simply run the .reg file to add the values to the registry.
This will get your updates back on Windows XP. Although we do have to say that this is an unofficial hack so ThinkComputers and Microsoft is not responsible if something breaks when using this hack. You do have to remember that Windows Embedded PoSReady 2009 and Windows XP are not exactly the same OS. Also this trick will only work on 32-bit versions of Windows XP.
Source: Myce | News Archive