PC World are wrong. I am using the product that they say does not exist! It is a Netgear FM114P wireless router with print server (click here). I bought mine from click here.
I have a desktop wired to it, the broadband modem wired to it and a laptop with a wireless card attached to it.
There is a setting on the router's software that allows a wireless connection to the internet but not to any network. This would be useful as you can use the internet but no-one can access the laptop's files (and you'll not be able to access anything on your wife's office PC from the laptop).
Also, as long as you don't share any files or folders, then there will be no access to them from the network.
The model I have also has a built in print server so I have a printer connected to it and I can print from any wireless/network machine without having to have the desktop nearest the printer switched on.
Negear/Dabs have a model without the print server function at a lower cost if you do not need that function.
Hope this helps