System Id on NT?

I need to recognize one computer exactly. How should I do, I cannot find any sysid. I've tried with system info of the cpu, nt version but I can easily find another PC with same number. How should I do?
Thanks in advance.
Cedric.

[Gomez Addams]

One common choice is the serial number of the system drive.
GetVolumeInformation can obtain this for you. The main difficulty
to this approach is dealing with the case where the hard disk fails
and/or is replaced.