finding product key on installed machine

[Phil Partridge]

Is there a way to find the product key with which Office
was installed on a particular machine?
I have searched, but cannot find it.
I am replacing some machines, and wish to install the
software on the new machines, but their is no record of
which copy was installed on which machine.
If I can find the relevant copy, I can install it on the
new machine, keep a record, and keep things legal.

Many thanks,
Phil Partridge