ReactOS - A Free Windows Clone
ReactOS 0.2
ReactOS 0.2.9
ReactOS 0.3.10

98lite - Windows without IE
98Lite Version 1.3
98Lite Version 2
98Lite Version 4.5

Microsoft Windows (Classic)
Microsoft Windows 1983 pre-Version 1.0 demo
New: Microsoft Windows 1983 Comdex Demo
Microsoft Windows 1984 Pre-release
Microsoft Windows Version 1.x
Microsoft Windows Version 2.x
Microsoft Windows Version 3.0
Microsoft Windows (Version 3.0) Graphical Environment with Multimedia Extensions 1.0
Microsoft Windows Version 3.10
Microsoft Windows Version 3.11
Windows 3.2 (Chinese Windows 3.1)
Microsoft Windows Chicago Build 58 - August 1993
Microsoft Windows Chicago Build 73 - November 1993
Microsoft Windows "Chicago" Beta-1
Microsoft Windows 95 (Version 4.0)
Microsoft Windows 98 (Version 4.1)
Microsoft Windows ME (Version 4.9)

Windows NT based
Microsoft Windows NT 3.1
Microsoft Windows NT 3.51
Microsoft Windows NT 4.0
Microsoft Windows 2000 (NT Version 5.0)
Microsoft Windows XP (NT Version 5.1)
Microsoft Windows Server 2003 (NT Version 5.2)
Microsoft Windows Vista (NT Version 6.0)
Microsoft Windows 7 (NT Version 6.1)
Microsoft Windows 8 (NT Version 6.2)

Assorted
Misc Windows Screen Shots (AKA "Sick Windows Tricks")
Misc Windows Screen Shots 2 (or "Sick Windows Tricks 2!")
New: Misc Windows Screen Shots 3 (AKA "Sick Windows Tricks 3!")