Here's the site for downloading BB Aus torrents...
http://www.bigbrotherbinaries.net/
Some adverts and previews are there at the moment. I might check this series out, at least until BB7 UK starts.
Don't forget to install the bittorrent client before downloading torrent files... here -->
http://www.bittorrent.com/download.myt
Here's a simple guide to bittorrent if you need more info -->
http://www.toritraders.com/guides/bittorrent.htm