I have a bit torrent question?

ok so heres what im trying to figure out i use bit torrent software mainly bitspirit to download my torrentsi connect wirelessly over the network 802.11n reciver and router i have a 1.5MB connection my roomate uses the graboid video service and he can usually connect at 1.5 to 1.6 MBs if im not on my other roomate plays linage(spelling?) but as soon as i start downloading even with limiters on such as the built in limiter and having netlimiter 2 pro on i still (supposedly) manage to bog down the entire conection to where the other 2 rromates cant even connect even if both programs say im downloading around 100KBs(sometimes upto 200KBs) so im trying to figure out if there is A.) if i truly am using way more then it says i am and why, and B.) if it is me thats doing it is there a way to control it or no i'd really love to be able to continue my bit torrent use but not at the expense of not letting my roomates get on to play