so you want to change your mac address
for this you need to have a little bit knowledge on windows registries
Step1
click on startbutton and click on Run and type regedit
Change Your MAC Address (Windows 2k/xp)
This setting will change the MAC address of the NIC card.
Go to “HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4D36E972-E325-11CE-BFC1-08002BE10318}. Double click on it to expand the tree. You should see it starts with 0000, then 0001, 0002, 0003 and so on.
Now go through each subkey that starts with 0000. Click on 0000, check DriverDesc keyword on the right to see if that’s the NIC you want to change the MAC address. The DriveDesc should match the Description of the NIC that to be chaged Example : DriveDesc REG_SZ D-Link DFE-520TX PCI Fast Ethernet Adapter. Now create REG_SZ with value name “NetworkAddress” .In the value data give the new MAC address .
System Key: [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Contro l\Class\{4D36E972-E325-11CE-BFC1-08002BE10318}]
Value Name: NetworkAddress