you could try to use
Azureus - now called Vuze, it's pretty slick looking and does have a ton more feature/options. As far as being lighter, i only have it's own claims to support that statement.
what may be possible, i don't know, is trying to go into your wireless router and 'throttling' your roomies connection.
or if you got money and time you can try to build yourself a mini-server and hook it up to a static ip (which some isp's provide you with at least one) and just have that dedicated to torrenting.