check the ip address. if your on virgin and it starts with 169 instead of 192 you will need to contact them as they will need to adjust the settings at there end to allow your wireless router to activate.
had this issue with mine last week when i tried to use my sisters lappy wirelessly for the first time. i ended up reinstalling windows only to find the problem was still there. i called the isp u and within 5 mins it was working fine. (wasted a full day for nothing)...
if your not on virgin you may still have the same issue as not all isp's activate the wireless functionality (even when its on on the router) at there end until you ask for it.