Simply put you need a router without an inbuilt modem. The router can be connected to any modem, cable or ADSL using it's WAN ethernet port.
There are a number of routers available, but many users on here have favoured those by Linksys. Since you already have some Linksys kit, that might suit you too.
A suitable model might be the Linksys WRT54G series assuming you are happy with the 54Mbps maximum wireless speeds. There are many versions though. The Linux model WRT54GL which some have found easy to update the firmware on is available for around £42.00
http://www.overclockers.co.uk/showpr...odid=NW-052-LS
See my post #2 above, for how to connect and setup. There should be no settings to load into the router to get it online, but you will need your account details to register the router with the Virgin Media server, which you do online through your browser.