http://support.microsoft.com/kb/224609

1.0 Included with Windows NT 3.51 SP 3 (or as a self-contained download). Windows NT Server 3.51
2.0 Included with Windows NT Server 4.0. Windows NT Server 4.0
3.0 Included with Windows NT Server 4.0 Service Pack 3 (Internet Information Server 2.0 is automatically upgraded to Internet Information Server 3.0 during the install of SP3). Windows NT Server 4.0
4.0 Self-contained download from http://www.microsoft.com or the Windows NT Option Pack compact disc. Windows NT Server 4.0 SP3 and Microsoft Internet Explorer 4.01
5.0 Built-in component of Windows 2000. Windows 2000
5.1 Built-in component of Windows XP Professional. Windows XP Professional
6.0 Built-in component of Windows Server 2003. WIndows Server 2003
7.0 Built-in component of Windows Vista and Windows Server 2008. Windows Vista and WIndows Server 2008
7.5 Built-in component of Windows 7 and Windows Server 2008 R2. Windows 7 and Windows Server 2008 R2
8.0 Built-in component of Windows 8 and Windows Server 2012. Windows 8 and Windows Server 2012