Basically its really simple, the modem is in my room, a LAN connection goes downstairs and theres several laptops in the house. I want to see whats going on, on those laptops, particularly mine while someone else is on it.
If I'm not mistaken then there are programs that allow you to 'sniff' packets sent from the computers on your network to the router. The last one I had a play around with was called Cain (and Abel). Though one of my friends mentioned something about being a script kiddy. I dunno maybe he was some 1337 h4x0rz... Can't hurt to give it a try though.