Does the laptop have an internal wireless card? If not you will need a
These usually come with a short cable which you should use rather than have this plugged directly in to the laptop (this will break sooner rather than later if plugged in directly). Also bare in mind the distance from the wireless router as the basic one supplied by Virgin only transmits a short distance (ours manages 15 feet or so horizontally).
Don't know about X-Boxes but Wii have an internal wireless connection and ours picked up the router signal easily.
We are connected PC to standard Modem then Modem to wireless router. Touch wood it all works well.