Xbox live! Help Me!

Hello, I'm trying to get connected to Xbox live but its not working with my modem.. I tried going to "Start" then run and "cmd" typed in "ipconfig" and all of that.. i went to network settings on my Xbox and i type everything in manually. Its still not working.. I was wondering if it was my modem.. I use to go on Xbox live all the time but i had a different modem from Comcast and it was silver. I just really want to connected so i can play online.. Please help.. Thnxx..