Just had a thought. If my router is disconnected but other computers are connected by router switch and plug the dongle into one computer on the LAN network via ethernet will other computers on the LAN see the dongle or does the dongle need to be connected to each computers USB port in order to surf the web. Hope that makes sense.
As per 5km's post, ICS is a cheap/free solution to share the connection from the dongle ... but it can be a fairly inelegant / manual / quirky solution to set up for a "quick-changeover" for backup-connection purposes.
I'd personally recommend one of these Zoom-4501-Routers as a better solution IF you reckon it's worth (to you) the £40 for a Full Ethernet + WiFi & Instant-Automatic-Changeover backup solution :-
http://www.ebuyer.com/product/174406
I use this with the solution we discussed via PM ... It's excellent, and also gives me the added advantage of using the same entire dongle+router system for FULL Mobile-Broadband-Wifi when we're away fron home in the car or caravan or on holiday (all that's needed is to add the "in-car power adaptor").
Edited by deleted (Sat 29-Jan-11 00:22:28)