Windows 2003 Server
Windows Neptune/5.5.5111.1 - BetaArchive Wiki
Windows XP Embedded 2014, Windows Never Released Wiki
Switching Windows XP/Server 2003's billboard without 3rd-party
Windows XP (NT 5.1)
Is Windows NT an application software? - Quora
Windows XP (NT 5.1)
WinWorld: Windows SDK & DDK XP (NT 5.1)
Windows 2000 (NT 5.1 update), OS Mockups Wiki
I made a large Windows Versions list! : r/windows
Types of Operating System