Windows Version

Future versions

• 2009 - Windows Server 2008 R2
• 2009 or later - Windows 7 (formerly codenamed Vienna, and before that, Blackcomb), slated to be Vista's successor,
• Windows Server 7, slated to be Windows Server 2008's successor
• Windows Mobile 7 for mobile devices

Cancelled versions

• 1999 December - Windows Neptune was sent out to beta testers but was never released. Should have been a consumer version (i.e. home edition) of Windows 2000.
• 1996 May 3 - Windows Nashville (Windows 96) (cancelled) (Became Windows 95B.)
• 1991-1998 - Cairo (a "true object-oriented OS") planned after Windows NT

Take from wikipedia.com