Hi Gilles you have a standard Cable Modem probably an Ambit 256 with Virginmedia on the front of it, to go wireless you require a Wireless Router link below for a Netgear one.
This is a Netgear WGR614 and is £24.99 if ordered online for instore pickup.
http://www.pcworld.co.uk/martprd/sto...&category_oid=