iMac G5 with 3G USB dongle question.

I just got my iMac G5 back up and running (I had to replace the hard drive) and now have an extra iMac here at home. I was thinking of taking it to work so I can have a computer there, but came to the realization that I cannot use the only phone line there for an internet connection. What I have thought of doing is buying a 3G USB dongle and using that as my wireless internet connection. I realize that I would have to purchase a wireless plan, most likely through AT&T much like on the iPad. Is it possible to just hook up one of the USB dongles in one of the machine's USB ports and going from there? Or will I need to purchase a wireless router in which to plug the USB dongle and then connect the iMac to the router with an ethernet cable?

You won't need a wireless router by using a dongle. However, most of what I have read from others regarding using a USB wireless dongle on the Mac is that they are difficult to get working. Also keep in mind that wireless plans from AT&T, Verizon, T-Mobile, etc are not inexpensive.

Here's a LINK that you can go to and price out various USB wireless dongles that work on a Mac.