I have found a Wannacry security patch from May 13, 2017 for windows xp. http://www.catalog.update.microsoft.com/Search.aspx?q=KB4012598
Here is NoMoreCry a vaccine for Windows 2000 http://fixmibug.com/nomorecry-spanish-vaccine-the-ransomware-wannacry.html#
Download link https://loreto.ccn-cert.cni.es/index.php/s/tYxMah1T7x7FhND
Does Wannacry affect Windows 2000? https://social.technet.microsoft.com/Forums/windowsserver/en-US/d6ad3131-65b7-495f-abe3-4efd9f3fa526/any-wannacry-patch-for-windows-2000?forum=winserversecurity
Here's a good argument for when someone says Windows NT 5 is not safe.
Top 50 Products By Total Number Of "Distinct" Vulnerabilities: http://www.cvedetails.com/top-50-products.php