POSReady 2009 is an embedded version of Windows XP and the patches are said to be fully compatible with Windows XP installations. If you're still running Windows XP, you can get this unofficial Service Pack over here but we highly advise upgrading to a more modern, safer version of Windows.
POSReady 2009 fixes are said to be fully compatible with Windows XP installations, but it’s pretty clear that they cannot offer the same level of protection as the legitimate updates specifically aimed at this platform.Source: SoftPedia
“Windows XP Unofficial SP4 is a cumulative update rollup for Windows XP (x86). 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,” the developer says in the description of its pack.
“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. You can also scan for POSReady updates, because the POSReady trick has been included. In addition, all post-eol updates for .NET Framework 1.1, 3.5 and 4.0 until May 2014 have been included.”