The following is a list of what MetaCard/Revolution presents when you ask for the systemVersion on various flavors of Windows:

Windows Version	systemVersion
Windows 95	Windows 4.0
Windows 98	Windows 4.10
Windows ME	Windows 4.90
Windows NT 4.0	NT 4.0
Windows 2000	NT 5.0
Windows XP	NT 5.1
Windows Vista	NT 6.0
Windows 7	NT 6.1
Windows 8	NT 6.2

Posted 6/9/2002 by Ken Ray
Updated 2/15/2006 by Ken Ray to include information on Microsoft Windows Vista.
Updated 11/28/2006 by Ken Ray to include information on Microsoft Windows 7. Updated 11/29/2012 by Ken Ray to include information on Microsoft Windows 8.