hi, the router has the external (virgin media) I.P address, something like 82.17.68.68 (yours will be unique) this is what connects to virgin, devices connected to the router also have unique i.p but these are not visible to the outside world, these are usually something like 192.168.100.100.
if you connect to your router using a p.c and using internet explorer enter
http://192.168.1.1 with a blank username and a password of admin.
this will enable you to check the router settings, security settign an router firewall,
this should enable you to check the settigns match your PS3, i would try and connect with the PS3 next to the router and then once connected move the PS3 to the desired location, because your problems may be caused by a simple lack / poor quality of signal