How to share USB wireless internet over a network

Hi

I have a slightly difficult problem
I have a USB wireless internet device connected to an iMac that I want to share over a network to other Macs (all os x 10.5). Can I use a simple switch or router or is this not possible at all? Really need some help.

Many thanks

Ive been wondering the same thing...

I have a usb720 aircard

A wireless router will work fine. Remember to turn on sharing in System Preferences. (under Network)

I do this on my macs using airport.
I don't have the airport router though, just the internal card.
I have a mobile internet usb modem in my iMac. (dongle)
Then in sharing I tell it to share the internet connection from the usb dongle via airport.
My airport icon on the menu then has a little arrow in it instead of the signal bar and all the other computers can connect to the internet through it a bit like my imac was a wireless router.