Finding the mac address of a windows machine is most easily done by typing “ipconfig /all” in the command prompt.
Hint: Verify that the mac for the correct interface is used. If there are several adapters (this list includes virutal adapters and vpn adapters).
In vista all you have to do is to open the control panel and enter uac in the search box, and you will find the correct option.
More info and about win 7 as well, http://www.howtogeek.com/howto/windows-vista/disable-user-account-control-uac-the-easy-way-on-windows-vista/