Officially, with the exception of one zero-day attack deemed too important to blow off, Microsoft will not give you any more updates to Windows XP.
Unless, of course, you can persuade them that it’s something else entirely:
As reported by Wayne Williams at Betanews and confirmed by us, a simple registry hack to a Windows XP system tricks Windows Update into providing updates for it.
Williams says that the hack … makes the system look like Windows Embedded POSReady 2009 which will continue to receive updates until April 9, 2019.
Caution: this seems to work only on 32-bit versions of XP, and Microsoft, of course, disavows any responsibility for the results.