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The code names "Vienna" and "Blackcomb" were both given to Windows 7.
Windows Blackcomb was announced in 2004, renamed to Vienna in 2006, and was later renamed to Windows 7 in 2007.
Windows 95: Chicago
Windows 98: Memphis
Windows ME: Georgia
Windows 2000: Neptune
Windows XP: Whistler
Windows Vista: Longhorn,
Windows Seven: Blackcomb
Windows Vista and Windows Server 2008 both shared the codename "Longhorn" during development at Microsoft.
Whistler Blackcomb