How do I change the MAC address of my network card?

"I have used these instructions in the past and they work great

There’s a C++ command-line utility called Macshift that allows Windows XP users to change their MAC address to any other valid address. I’ve written about how to use it and how to create shortcuts to change your MAC address on-the-fly. I’ll first explain how to use Macshift for any MAC change, then I’ll show you how to make Windows shortcuts using the command-line options. I’ve also made a small script to make it easier to use, but the script isn’t necessary.
Macshift usage
Macshift is a command-only utility, so you need to learn the options to use it."

"Go into properties for Network Connection. Click ""Configure"" next to desired network adapter and on Advanced tab you should have one field for MAC address. Usually it is named ""Address"", ""Locally Administered Address"" or something similar. There you have text box in which you can type desired MAC.

Take care that you turn off original PC (or change it's MAC also)."

"It is worth mentioning that in a MAC address the least significant bit of the first octet is a multicast flag (multicast addresses have it set to 1), so the adapter's address should normally have it set to 0. This means that valid values of the first octet must end with 0, 2, 4, 6, 8, A, C or E.

Moreover, the second-least-significant bit of the first octet is used to distinguish between globally and locally administered addresses (if it is 1, the address is locally administered), and certain adapters (e.g. Intel Wireless) may enforce this by not allowing to change the address to another ""globally unique"" one. Hence, the value of the first octet must end with 2, 6, A or E."

"You don't specify your OS, so I'm assuming a Windows flavor. Here's a decent writeup of changing MACs on Windows as well as a wide variety of other systems.

Note that that page and Systech's link both recommend a program called Macshift that's listed as WinXP ONLY."

"Some network adapters allow you to change the MAC address of a network adapter through their configuration dialog:

An example is shown in this screencast. But please keep in mind that this doesn't relate to all network adapters!"