Virgin can come down a "phone line" or "cable" and you need to find out which you have.
Then you need to buy a router for a phone line (normaly marked ADSL I think) or a router for cable (normally marked as a cable router).
If you look at this page here from PC world, see it shows a section for "ADSL routers" and another for "Cable" routers.
http://www.pcworld.co.uk/martprd/editorial/net working_homepage/?int=top_nav
Dont buy one until you are certain what type of Virgin line you have: ADSL or Cable.