//Добавляем:
//в references
//System.Management.dll
//в директивы
//using System.Management;
var mbs = new ManagementObjectSearcher("SELECT * FROM Win32_DiskDrive");
ManagementObjectCollection mbsList = mbs.Get();
string id = "";
foreach (ManagementObject mo in mbsList)
{
id = Convert.ToString(mo["SerialNumber"]);
break;
}
return id;