How to connect a second laptop to the internet using wireless adapter?

Hi! Please can you tell me how to connect a second laptop to the internet using a wireless adaptor? It keeps asking for a network key (WPA) The laptop I am using now is vista and the second laptop which I am trying to connect is XP, does this make a difference? I have asked AOL tech support but have got nowhere!! please, please can someone help me? The router is a NETGEAR DG834G, the wireless adaptor is a BELKIN G+ USB adaptor, the first laptop is a HP COMPAQ 6720s and the second laptop is a DELL LATITUDE D600. Thanks! Angie