Installing Microsoft Loopback Adaptor

Microsoft Loopback Adapter is a virtual/dummy network card, there is no hardware required for this. It create virtual network environment where network access is not available. You can install microsoft Loopback Adopter very easyly just follow following steps:

Changing the MAC address in W2K and XP

Change Network Interface Card (NIC) MAC address, for windows 2000 & XP

1. Go to Start->Settings->Control Panel and double click on Network and Dial-up Connections.
2. Right click on the NIC you want to change the MAC address and click on properties.
3. Under “General” tab, click on the “Configure” button
4. Click on “Advanced” tab
5. Under “Property section”, go at “Network Address” or "Locally Administered Address", click on it.
6. On the right side, under “Value”, type in the New MAC address you want to assign to your NIC. Usually this value is entered without the “-“ between the MAC address numbers.
7. Goto command prompt and type in “ipconfig /all” or “net config rdr” to verify the changes. If the changes are not materialized, then use the second method.
8. reboot your computer

Read more at : http://www.tech-faq.com/change-mac-address.shtml