Recently my friends and I got a ADSL line in our apartment. However we often have problems with some our internet connections cutting out for several seconds whenever one of us is using Bittorrent. For example, I could be playing an online game, and one of my friends could be using Bittorrent, and the connections for both of us would cut out or be unreasonably/unsually slow (especially considering average download speed on Bittorrent is only 150Kb/sec, and our modem can handle 350Kb/sec). However, if I am playing an online game, but someone else is downloading from another website like, for example, Fileplanet, nothing happens to our connections.
Operating systems of affected systems: Mixture of Windows XP Home & Prof
Router/Cable model model: Siemens Speadstream 6520 (combined modem and router)
Problem began: Whenever someone uses Bittorrent
Firewall: Windows XP built in firewall, and router's built in firewall
Other: Speed of ADSL: 3MB/sec download, and 800KB/sec upload
Please help ASAP. Thanks.