http://runescape.salmoneus.net/forums/inde...howtopic=235088You could have really posted it in that topic..

Anyway, I don't see why you need a hardware solution. There is software available, I am sure, that can monitor bandwidth on your network, otherwise you could just install the software onto each of the computers.
If you definitely need hardware for some reason, then I know of none. If you have a router, and have access to the router admin page, it may have some kind of meter on there - mine doesn't though.