Your broadband will not be able to pass through your V+ cable box.
When I booked the date to have V+ installed the person on the service desk who took my order for V+ arranged for an engineer to come the day before to install a router at the junction where it had previously entered my old cable box. She gave me the option of sending the router through the post but as the engineer was free of charge I opted for ntl to do it. There was no alteration to the cabling at all.
My broadband connection seems faster (maybe wishful thinking) and I no longer have the the problems with connection- no more running downstairs to unplug etc.
Jo
add. according to the sevice desk staff, in the manchester region the engineers who install V+ do not do broadband