If you and your roomate want to use bittorrent, then you would need to split forwarding your ports on your linksys. You and your roomate should use static ip's so the port forwarding does not forward to an address your no longer at. Also, don't forget you would get differnt ip's depending on if you use wireless or wired connection due to different mac addresses.
For example:
You= 192.168.1.10 forward ports = 6881-6885 to 192.168.1.10
Roomate= 192.168.1.11 forward ports = 6886-6889 to 192.168.1.11
Also make sure you don't have any software firewalls blocking anything like Zonealarm, McAfee, Norton, etc.