I had a problem with my netgear dg834g v2 router. I had a PC and two wireless laptops. The wired PC connection, internet was fine. With the other two laptops, they would connect to the wireless network but couldn't connect to the internet. It kept displaying "IP Adress unobtainable etc".
Been 9 MONTHS trying to sort this out.
Eventually all I had to do was turn off WEP, connect again, and worked fine.