On Sat, 05 Jan 2013 18:34:51 -0500, GS wrote:

I recommend using WMI to obtain the BIOS serial number because all the
values recommended by you and Isabelle (thus far) can be
edited/changed. The only way to change the BSN is to replace the
motherboard. In the case of a clone machine returning an empty BSN, I
substitute with a hash value of that empty string via SHA256. When this
is combined with make & model it serves well enough for my purposes.<g

Oh, and my machine is built by myself; your routine returns "To Be Filled By O.E.M." (Which is what is in all the Chassis Information slots except for Type: Desktop)