Windows 2001

Windows 2001 is released in April 22, 2001. Mainstream support end only on June 15, 2012.

Editions
Windows 2001 Professional (2001-2012)

Windows 2001 Plus! (2001-2012)

Windows 2001 Server Family (2001-2012)

Windows 2001 NET. Server (2001-2012)

Windows 2001 Starter (2001-2007)

Windows 2001 Home Edition (2001-2009)

Windows 2001 Media Center Edition (2001-2008)

Windows 2001 Embedded (2003) (2003-2011)

Windows 2001 Slim (2006) (2006-2010)

Windows 2001 Ultimate (2001-2010)

Windows 2001 SE (2004) (2004-2012)

Windows 2001 TE (2009) (2009-2012)

Windows 2001 FE (2010) (2010-2012)

Windows 2001 Server (2001-2012)

Windows 2001 Server R2 (2002) (2002-2008)

Trivia
Windows 2001 has combined with Whistler and XP.

The only but was end of mainstream planned to end on June 15, 2012 for some reason.