How to tell if the Office Product Key is valid?

[TomT]

I received Office 2003 Pro and Office Ultimate 2007. Both are original CD
with product key labels. Does anyone know how I can tell if either product
was already registered by the original user? Both copies came with claims
that they were not registered.

Thank you.

 

[DL]

You cannot tell; and I assume you mean activated, and that they were not
supplied with sealed media.