Office 2000 update problem / registry key change

[Eric]

I inherited some problems with this job and the largest
problem has been finding the correct disk to update thier
Office suite (2000 & XP). We are a university and have a
site liscense for our software, but many of these
computers were purchased with the office suite
installed....but nobody in the offices knows where the
software is.

Is it possible to change the product key on currently
installed versions of Office 2000 or Office XP from the
original lost copies to our site liscense numbers? It
sure would save me quite a bit of time rather than un-
installing the suite and re-installing with another set of
disks.

Thanks for any help/advise!

Eric "the lone tech"