Q:

was my windows installation upgraded from previous version

How can I tell whether the current windows installation was ugpraded from a previous version or edition?  Does the registry or filesystem have data that would tell me? 

A:

There is a key called MediaBootInstall in the registry under HKLM/Software/Microsoft/Windows/CurrentVersion/Setup/OOBE/, which is set to 1 if you do a clean install via DVD/ISO and the value is 0 if you do an upgrade.