If you would like to use Bit Torrent behind a Windows XP firewall, then you will probably need to follow the steps below:
1.> Open the 'Network Connections' folder (click Start, then Control Panel, then Network and Internet Connections, then Network Connections.)
2.> Click the shared connection or the Internet connection that is protected by Internet Connection Firewall, and then, under Tasks, click Change settings of this connection.
3.> On the Advanced tab, click Settings.
4.> For each port you wish to forward, (i.e. 6881, 6882, ... 6889) do the following:
4.1> On the Services tab, click Add and enter all of the following information:
4.2> In Description of service, type an easily recognized name for the service, such as "BitTorrent".
4.3> In Name or IP address of the computer hosting this service on your network, enter 127.0.0.1 (this means "the local machine.")
4.4> In both External and Internal port number for this service, enter the port number, e.g. 6881.
4.5> Select TCP, then OK.
You are done :)
Hope this helped you.