WMI and program protection

[Ably+]

I have part of code where getting "real" HD SerialNumber. My intention is to
use it for protection of my application. I am not sure is that a good idea?

Anyway, code below reads all HD (more than one if are present) and I would
like to read only one disk, on c:\ if is possible.

ManagementObjectSearcher searcher = new

ManagementObjectSearcher("SELECT * FROM
Win32_PhysicalMedia");

int i = 0;

foreach(ManagementObject wmi_HD in searcher.Get())

{

// get the hardware serial no.

if (wmi_HD["SerialNumber"] == null)

SerialNo = "None";

else

SerialNo = wmi_HD["SerialNumber"].ToString();

++i;

}

Well, I would like to know is possible to get a serial number of HD only for
main disk?

What are you thing is better to use CPU number or something in order to set
a good program protection?

Thanks in advance.