There are tools that can accomplish this for you, like this one,
http://ntu.csie.org/~piaip/docs/Change_MAC_w2k.htm
Or there are a couple of methods you can try manually
Method 1:
Some network cards have a "spoof MAC configuration" built in, if yours happens
to have this, then use this method.
1. Go to the Control Panel and double click on Network and Dial-up Connections.
2. Right click on your card and click on "properties"
3. Click on the configure button under the general tab
4. Click on the "Advanced" tab
5. Under the Property section, click on "Network Address" (or "Locally
Administered Address")
6. Under "Value", (on the right side) type in the New MAC address you want to
assign to your card.
7. Run an "ipconfig /all" or "net config rdr" to confirm the changes.
8. Reboot
Method 2:
Windows 2000/XP
1. Start the registry editor (Run - regedt32)
2. Go to " HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Contro
l\Class\{4D36E972-E325-11CE-BFC1
-08002BE10318}". Double click on it to expand the tree. The subkeys are 4-digit
numbers,
which represent particular network adapters. You should see it starts with
0000, then 0001,
0002, 0003 and so on.
3. Find the interface you want by searching for the proper "DriverDesc" key.
4. Edit, or add, the string key "NetworkAddress" (has the data type "REG_SZ")
to contain
the new MAC address.
5. Disable then re-enable the network interface that you changed (or reboot the
system).
For WIN9x
Use the Windows 2000/XP method, except go to the registry key: "
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Servic
es\Class\Net"
When done, you must restart.
