Change the MAC Address of NIC in Windows via Registry

Open a command prompt.
Type the following command and hit Enter.
ipconfig /all
Record down the Description and the Physical Address (is MAC address) of the active network connection (discard those with Media Disconnected state).
For example, in figure above, Description is Intel(R) Wireless WiFi Link 4965AGN and MAC address is in the format of 00-XX-XX-XX-XX-XX.
In the command prompt also, type the following command and hit Enter.
net config rdr
Record down the GUID for the MAC address for the active connection’s NIC which MAC address to be changed. The GUID is contained within the { and } brackets right in front of the MAC address as shown in figure below.
Type regedt32 or regedit in Start -> Run box or in Start Search for Windows Vista. Note: for Windows NT 4.0 and Windows 2000, regedt32 must be used.
Navigate to the following registry key:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4D36E972-E325-11CE-BFC1-08002BE10318}
Expand the {4D36E972-E325-11CE-BFC1-08002BE10318} tree, and there will be more sub-keys in the form of 0000, 0001, 0002 and so on.
Go through each sub-key starting from 0000, look for subkey that has DriverDesc value data that matches NIC description copied from step above, that want its MAC address to be changed. In most cases, it will be similar to the network adapter card name.
To verify that the subkey found is indeed a correct one, check the value of the NetCfgInstanceId, which should have the same value with the NIC’s GUID taken from step above.
Once a sub-key is matched to the network interface card that MAC address want to be spoofed, select and highlight the subkey. Right click on the sub-key (for example, 0000), then select New ->String Value. Name the new value name as NetworkAddress.
Note: If NetworkAddress REG_SZ registry key is already existed in the right pane, skip this step.
The double click on NetworkAddress and enter a new MAC address as its value data.
Note that the 12-digit MAC address in hexadecimal format, and should be entered without any dash (-). For example, 1A2B3C4D5E6F.
Reboot the system to make the new MAC address effective. Alternatively, if you don’t want to restart the system, try to disable and then re-enable the network adapter in Device Manager.
To verify the change of MAC address, go to command prompt, then type in one of the following commands:
ipconfig /all
net config rdr
Note: To restore or reset back to true original hardware burned-in MAC address, remove the NetworkAddress registry key that is been added.
Alternative: Third party tools and utilities to change the MAC address in Windows operating system are plenty, for example: SMAC (direct download link to smac20_setup.ex, supports Windows Vista, XP, 2003, 2000), Macshift (direct download link to macshift.zip, for Windows XP), BMAC (almost identical SMAC MAC changer clone by moorer-software.com), Mac MakeUp (direct download link tomacmakeup.zip, for Windows 2000/XP/2003/Vista), MadMACs (MAC Address Spoofing And Host Name Randomizing App For Windows, directly download MadMACs.zip), EtherChange (direct download link to etherchange.exe), and Technitium MAC Address Changer (for Windows 2000 / XP / Server 2003 / Vista / Server 2008).