Read post #5 -
http://www.project1999.org/forums/sh...ad.php?t=11286
My own guesses - your roomate is using a majority of the connection (ie. bittorent, etc).
Try speedtest.net, though I don't know if they have any testing sites in Australia. Definitely try the port forwarding mentioned in the link above. Ultimately, if you aren't controlling the internet connection and/or have other people using it, it's going to be difficult to troubleshoot connection problems. Running a speedtest and even just pinging some generic sites should give you a heads up if someone is really using a lot of the bandwidth.