If you have ADSL broadband via the phone line, you use a *combined* "Router & ADSL Modem", which connects directly to the phone socket. It replaces any USB Modem previously used.
With Virgin's CABLE broadband, you use a "Cable/DSL Router" which doesn't incorporate a Modem and which connects by ethernet cable to Virgin's supplied Cable Modem.
When you use a Router, it [the router] gets the IP address allocated by the ISP and in turn allocates IP addresses to each computer connected to it, using one of the address ranges reserved for Local Area Networks, most commonly a 192.168.x.x address.
It is the Router which must be configured to connect to the internet and then the PCs get their internet access over the LAN (Local Area Network) from the router.