No connection found

I have a cable modem, and a linksys Router, my main computer is a dell 2.0 ghz, and my secondary is a generic 1.5 ghz. when I attempt to get a network / internet connection on both of them, I get nothing, yet when I unplug the 1.5 ghz system it works for the internet. I am using linksys software to locate the ISP, and most of the time it will not find it. Should I use the windows network setup instead? Where can I find a simple process ladder to do this netowk setup?