Well I myself have windows update turned off. Don't know if that will stop windows from using your bandwidth. You can do this by holding down your windows key then hit your pause break key at the same time which will open your system properties then go to your automatic updates tab and then check the turn off updates. Don't forget to go back and turn it back on when you are done downloading. If you have any tech questions this is a great site to ask and recieve help for any off your questions or problems.
http://forums.techguy.org/index.php?