Product progression

Original line

    * Windows 1.0
    * Windows 2.0
    * Windows 2.1 aka Windows/286 and Windows/386
    * Windows 3.0
    * Windows 3.1
    * Windows 3.11 aka Windows for Workgroups
    * Windows 3.2

Windows 9x

    * Windows 4.0 (Windows 95)
    * Windows 4.1 (Windows 98)
    * Windows 4.9 (Windows Me)

Windows NT

    * Windows NT 3.1
    * Windows NT 3.5
    * Windows NT 3.51
    * Windows NT 4.0
    * Windows NT 5.0 (Windows 2000)
    * Windows NT 5.1 (Windows XP)
    * Windows NT 5.2 (Windows Server 2003 and Windows XP Professional x64 Edition)
    * Windows NT 6.0 (Windows Vista and Windows Server 2008)
    * Windows NT 6.1 (Windows 7 and Windows Server 2008 R2)

   
— Wikipedia on History of Microsoft Windows

2011.02.26 Saturday ACHK