If you have a router capable of
Tomato you could flash up to it and use its QoS traffic shaping to throttle traffic, presumably your roommate was doing P2P or something else that was saturating your bandwidth. Set it in a lower queue, such as E, and only allocate 100Kb/s to that queue or whatever suits you best. That way it will only saturate 100Kb/s of your total bandwidth instead of all of it.
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