Sharing EDGE/UTMS/3G over a wired LAN?

Hey all. We've a cable connection at the office that's very fast. The router is connected to a large switch (lots of ports available) and shares the connection to the internet between 5 PCs.

As we've been experiencing problems with the connection, we've bought an USB dongle from a mobile/cellular operator.

I'm wondering what the best way is to share this backup connection amongst all pc's?

So far I've only been able to connect 1 PC to the net, but havent been able to figure out how to share the connection amongst the network.

I understand there are wireless routers that take these sort of cards, but we do not want to go wireless.

I do not understand how to "bridge" connections, but that's what I've got to do (apparently).

3/5 Pc's are Vista

2/5 (including the server) are XP.

All PC's have only 1 Ethernet card

Server has a fixed IP. All others are set to automatic.

Connection to net is through router thats connected to Switch

Thanks!

Thanks for the answer, it looks like an interesting product and I will look into it! However I would like to know if there's *anyway* I could have the setup working without investing in any other equipment; perhaps by using Microsoft Sharing tool? Thanks

Well, you are correct in that many of these routers CAN BE WIRELESS but they also contain ethernet ports so you can use wired! Check the DLink DIR-450. it does have BOTH wired and wireless (you can turn the wireless off if you don't want it).
http://www.dlink.com/products/?pid=524&s...



Both routers will be able to be used as fall -over they will not combine for better bandwidth but can be used as "if one fails - the other works" or "Load Balanced" (shouldn't be needed for 5 users!) You may need a bandwidth controller between them so that you can balance them. The easiest way is to use a router with DUAL WAN ports so that your cable connects to one and the 3G to the other- then let the router manage it.
Your FIXED/STATIC IP for the internet will only work with the current connection.. when you switch to the 3G or edge that IP won't be available.. Now if you mean a fixed IP on the LOCAL network you won't have any issues at all.

The setup needed
>>Main INTERNET -----> Port 1 Dual WAN --- Local network
3G/EDVO -Router 2 --------> Port 2 Dual WAN

Added:
well you can setup a laptop with ICS (internet connection sharing) BUT you will have some issues to deal with. One, since your local router is the DHCP server and you will need the ICS unit to NOT issue addresses.
Two, You will have to manually add the ICS machine into each computer as a secondary gateway so that if the main gateway fails the second gateway can be used. You should manually assign the ICS machine a static IP on the local network in order to do this.
Three, realize this is a very LOW performance method for networking (dedicated routers are much more effective and easier to setup and use.)

It is rather difficult to use in an existing network in this manner but it can be done. (If you fully understand networks and options etc in the advanced network settings!)