On Sat, 05 Jan 2013 20:33:38 -0500, GS wrote:

After serious thinking Ron Rosenfeld wrote :
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)

Interesting that this is the stored value. Obviously this is different
than what's returned in a commercial unit. For example, I find it
typical of clone machines released by Gateway to return an empty
string. Your case is a new one for me!<g

Some interesting further investigation, the significance of which I have no idea.
PCWizard returns the following in the "Mainboard" section:

----------------------------------------------
<<< Mainboard

Manufacturer : To Be Filled By O.E.M.

General Information
Product : To Be Filled By O.E.M.
Version : To Be Filled By O.E.M.
Serial Number : To Be Filled By O.E.M.
Unique ID : 00020003-00040005-00060007-00080009
SKU : To Be Filled By O.E.M.
Family : To Be Filled By O.E.M.
Start mode : Power Switch

OEM Information
OEM #1 : To Be Filled By O.E.M.

Chassis Information
Intrusion detected : Unspecified

Mainboard : ASRock Z77 Extreme6

General Information
Manufacturer : ASRock
Product : Z77 Extreme6
Version : Unspecified
Serial Number : Unspecified
Support MP : Yes, 4 CPU(s)
Version MPS : 1.4

Chassis Information
Manufacturer : To Be Filled By O.E.M.
Type : Desktop
Version : To Be Filled By O.E.M.
Serial Number : To Be Filled By O.E.M.
Asset : To Be Filled By O.E.M.
--------------------------------------------
So there does seem to be a UUID associated with this system.

In the original version of your Get_BIOSserialNum function, if I examine vBIOS in the Watch window and look at Qualifiers_ Item 4, I see, (in part):
: Name : "UUID"
: Value : "{8502C4E1-5FBB-11D2-AAC1-006008C78BC7}"
I don't really know what this represents.

If I modify your Get_BIOSserialNum function to look at Win32_ComputerSystemProduct, then the UUID returned is similar but not identical to that returned by PC Wizard:
vbios.UUID -- 03000200-0400-0500-0006-000700080009

Thoughts?