Use AVG free antivirus on each computer, and I use the free Kerio firewall (you should have both). Download and install on each computer. I also use one Bill D. recommended called WinPatrol, also free, that keeps an eye on my registry.

I guess I have to configure each computer to the router and each computer with a protection program of its own like AVG.   ?

One computer is hooked up to the router and is where you make adjustments. On that computer you need to open the router page (i.e., http://192.168.0.1) and set up the router to recognize and respond to any other devices you want to run on it.

My router is wireless (though I can hard wire computers from it) and I entered the MAC address of each device that is allowed access (the Linksys wireless card on the other computer, my son's Wii game, etc.) and also set up a password, told it not to broadcast that it was there, and to only respond to those devices.

SRS