The system requirements for Internet Explorer 9 are Windows 7, Windows Server 2008 R2, Windows Vista Service Pack 2 or Windows Server 2008 SP2 with the Platform Update. Windows XP and earlier are not supported. Internet Explorer 9 is the last version of Internet Explorer to be supported on Windows Vista; Internet Explorer 10 will only be supported on Windows 7 and later. Both IA-32 and x64 builds are available.