If you like to know the BIOS Serialnumber of a Windows PC, you can use WMI classes and a query like "SELECT * FROM Win32_BIOS" to get it.
Simply try it in our example project WMI Query. Compile the project on Windows, enter the query and run it. In the list of the values you get, you see SerialNumber near the bottom.
It should look like this:
31 08 12 - 22:48