DOS BASED WINDOWS

Windows 1.0
Windows 2.0
Windows 3.0 (the first version to make substantial commercial impact)
Windows 3.1x
Windows 3.2 (Chinese-only release)
Windows 95 (aka Windows 4.0)
Windows 98 (aka Windows 4.1)
Windows Millennium Edition (often shortened to Windows Me) (aka Windows 4.9)
OS/2 (developed jointly with IBM)
Windows NT
Windows NT 3.1
Windows NT 3.5
Windows NT 3.51
Windows NT 4.0
Windows 2000 (aka Windows NT 5.0)
Windows XP (aka Windows NT 5.1) (codename: Whistler)
Windows Server 2003 (aka Windows NT 5.2) (codename: Whistler Server)
Windows Fundamentals for Legacy PCs (aka Windows NT 5.1)
Windows Vista (aka Windows NT 6.0) (codename: Longhorn)
Windows Server 2008 (aka Windows NT 6.0) (codename: Longhorn Server)
Windows 7 (previously codenamed Blackcomb, then Vienna)
Windows Preinstallation Environment (WinPE)