Is there really any way to uniquely identify any computer at all

How about adding motherboard serial number as well e.g.:

using System.management;


//Code for retrieving motherboard's serial number
ManagementObjectSearcher MOS = new ManagementObjectSearcher("Select * From Win32_BaseBoard");
foreach (ManagementObject getserial in MOS.Get())
{
textBox1.Text = getserial["SerialNumber"].ToString();
}

//Code for retrieving Processor's Identity
MOS = new ManagementObjectSearcher("Select * From Win32_processor");
foreach (ManagementObject getPID in MOS.Get())
{
textBox2.Text = getPID["ProcessorID"].ToString();
}

//Code for retrieving Network Adapter Configuration
MOS = new ManagementObjectSearcher("Select * From Win32_NetworkAdapterConfiguration");
foreach (ManagementObject mac in MOS.Get())
{
textBox3.Text = mac["MACAddress"].ToString();
}

The fact in getting a globally unique ID is, only MAC address is the ID that will not change if you set up your system all over. IF you are generating a key for a specific product, the best way to do it is assigning unique IDs for products and combining the product ID with MAC address. Hope it helps.