For several years, I have used the small, free utility known as Magic Jelly Bean to document or determine the Windows and Office product keys installed on a computer. One limitation of this utility was that you had to run this utility at each computer individually.
Recently I discovered a similar utility – ProduKey – that will also scan all the computers in your network and produce a single report of the Windows & Office product keys installed. It also checks on Exchange and SQL product keys, which is great for our SBS environments!
Click on the attachment to see a screensnapshot of the results of running this on my home SBS network.