Help with Internet Connection!?

[PrettyP]

HELP! My Family is currently using Wireless Internet. The Internet is provided by an Antenna that's installed at the roof of our house. We live far from the City, so this is our only option for good Internet. Anyway, a Customer Rep. from the Company told Me that I'd have to purchase a router in order for the Connection to be shared on other Computers. So, I did. I also purchased USB Wireless Routers for the other Computers. Everything worked fine until recently. Every time I plug in the Router, the Main Computer gives Me an "Ethernet Cable is not Connection" message even though it is. When I unplug the Ethernet Cable that came with the Router and use the Cable My ISP put that gives the Main Computer the Internet Connection, everything works fine. Any ideas on what I need to do? Could the error have happened because I hit renew IP once on the other Computer? I've tried calling the ISP, but that's of no help. Also, I'd like to add that the Router that I've installed on the Main Computer lights up even though I am given a "Cable is Not Connected" error. Thanks for your time and help!