|Buy a SOHO Router that has a linux based firmware that can be replaced by Tomato firmware. Then using the QoS built into Tomato, you can shut bittorrent right off, or limit the bandwidth to such a small amount your roomie can't up/download anything.|
If that's not possible, if you can afford your own internet connection, I'd go that route.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.