Hey guys, hopefully some of you will be able to help me!

First off I have 2 PCs and an Xbox which will all require an Internet connection. I also have a USB Broadband modem. Here we go:

I understand routers plug directly into your modem from the phone line - without connecting to a host PC, and each device will have a Wireless Card (or similar)? Is this correct? And you can also get routers which have modems in them - in which case it's just them that connect to the phone line?

I think that is correct, but it'd be great if someone could clear it up. The problem is I have a USB modem, which would obviously cause problems here.

Is it possible for my 'host' PC to stay how it is, recieving the Internet directly from the USB modem, but it has something similar to a router plugged into a spare USB slot...which then sends the signals to other PCs with wireless cards etc.?

As you can see I really am quite unsure about how this all works and I would like to know exactly what I'm doing before I invest.

Thanks for your help!