Comcast Modem causing speed problems

[bravo106]

I have my main computer hooked up downstairs via wireless from my linksys WRT54G. The modem that comcast provided is an Arris TM502G. I have the modem hard lined into the router then the router broadcasting the wireless. I have configured the router to have a port open for my computers static ip and utorrent work perfect when i had my computer connected to the router with a cable but after I moved I had to switch to using a wirless connection. I tried to redo the static ip but now whenever utorrent is active instead of connecting to the routers ip it uses the modems ip. I have the port forwarded on the router but I do not know how to do this on the modem or how to change utorrent so that it connects using the routers ip. Any suggestions would be helpful. Thank you.