Sign up for the cable internet. You'll have to install a cable modem at one of the TV jacks. Then get a broadband router. All the computers will plug into the router via ethernet cable and then all can go on the internet simultaneously. If a computer doesn't have an ethernet adapter, you'll have to install one, but they are inexpensive and installation is easy. If your computers are not located near each other and you can't/don't want to run ethernet cables all over the house to connect the computers to the common router, then you'll have to choose a router that has wireless networking and install wireless adapters in the distant computers. This will also introduce security issues, as intruders can eavesdrop on the wireless transmissions (or worse, someone can sit on the street outside your house and use your internet connection for nasty deeds), but you can learn how to lock down your wireless connection.