Get the Serial Number with Visual Basic

Hi folks,

I have to write a Visual Basic 6.0 Program and need to uniquely identify a
computer in a network and the user mustn't be able to change that id while my
program is running. So the Volume Serial Number of the HDD isn't a possibility,
because you can set the Volume SN whatever you want and therefore it's not
unique in a Network. I heard that there's a manufacturer's Serial Number on the
HDD that can't be changed and that is unique (worldwide?). How can I get that SN
with VB6? Or do you have any other ideas? Like a BIOS SN?

Thanks a lot in advance,

Michael
PS: Answer in German is ok.