cat74:
the wireless router needs to be attached on the landladys machine, then anyone else can access it via wireless
Actually, modem/routers don't need to be attached to any computers. They work on their own and computers connect to them either through a wired ethernet connection or a wireless connection. (wireless is new and not as good as ethernet, which why it's still availible).
To set it up you'd generally plug the router into a power socket and the wall socket (via a microfilter usually). You then connect all the computers to it either via wired or wireless.
Desktops don't come with wireless as often as laptops so your son may need to buy a wireless networking card for his desktop.