If your Windows NT was upgraded from Windows 3.1x, the UpdateMode value name, a type REG_DWORD entry, will be set to a 1 at:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Update

You can test this in a batch using kix (tip 120), or REG (tip 170), or the Resource Kit utilities (tip 107).

To determine your current Windows NT version, look at:

HKEY_LOCAL_MACHINE/SOFTWARE/Microsoft/Windows NT/CurrentVersion

 Value Name   Type   D e s c r i p t i o n 
 CurrentVersion   REG_SZ   4.0, 3.51, 3.5, 3.1 etc.. 
 CurrentBuildNumber   REG_SZ   NT 4.0 is build 1381. 
 CSDVersion   REG_SZ   Service Pack 3 or Service Pack x, RC n.nn for a beta build. 
 InstallDate   REG_DWORD   Time (in seconds) since 12:00 A.M, January 1, 1970 
 SystemRoot   REG_SZ   The Windows NT folder name.