Telling us that you have Comcast helps, but there is lots more that you didn't tell us.

What router are you using? You are using a router, are you not? What's your NIC? Why do you think you need a proxy? What settings are you seeing when you try to connect? What is the output of ifconfig and netcardconfig? Are you sure that you are not already on the Internet after booting? Why in the world did you post this in the General Support forum when we have a Networking forum?