How can I tell what version of Windows is installed on a hard drive without booting it?

1. you can open the file ../Windows/System32/license.rtf with Word pad. Guess what, it tells you EXACTLY what system is installed. On that same drive above, this file said "WINDOWS 8 PRO"
2. Look in the ../Windows/System32 folder for a file called "ntoskrnl.exe". If this file exists, it is at least an NT based system. (I assume you are not looking for Win95 or earlier.)
   
   Now do a properties and examine the details for a product version.
   
   4.x: NT 4.x
   5.0: Windows 2000
   5.1: Windows XP
   5.2: Windows 2003 Server or Windows XP-64-bit
   6.0: Windows Vista
   6.1: Windows 7
   6.2; Windows 8
   6.3: Windows 8.1
   
   This does not however  tell you which flavor of those systems (Pro, Home, etc).
3. Look at the following file(s) on the hard drive ../windows/system32/eula.txt