There are many reasons why one might want the BIOS Key (btw bios keys only exist in national brand computers that were shipped with windows 8.0, 8.1 or 10)
It is a valid install key for the windows that was shipped with the machine. It is also a valid key for use in installing and activating windows 10.
Let's say that you got a PC that was shipped with windows 8, but really wanted windows 7 and had a valid windows 7 retail install key and installation media.
So you install windows 7 on the machine. It will not take the embedded BIOS Key.
So after you have been using windows 7 for a while and now you want to upgrade to windows 10.
It would be foolish to use your windows 7 key for this because there is an embedded windows 8 key in BIOS that will do this nicely.
The trouble is that this key only exists in BIOS and you need a special tool to read it.
So the procedure would be extract the BIOS Key, disconnect the internet(important), perform the upgrade to windows 10, then go to 'system' applet from control panel and change the key to the windows 8 BIOS Key before you reconnect the internet to activate
Now you can use that windows 7 key on another machine. And you can then activate a windows 10 upgrade on that machine with that windows 7 key as well.
So when I originally asked the question, the only tool that would properly read the BIOS Key on a windows 7 PC was to use the Self booting puppy CD described above. Firmwaretablesview then modified their code to work under windows 7 and I have been using that to extract the key,
However, having just tried the showkey program referenced above, I will use that in the future. It's a much better written program.