Vista Home Premium sp 1
Router Linksys WRT54G2 V1

Using above described router for my wireless home network, we have 3 laptops on the network, 2 of them are working just fine connecting wireless to the router and the Internet, 1 of them can connect to the router but not to the Internet (thru the router). If I connect the laptop directly to the modem (no router) it connects right away to the Internet.
the message "cannot connect to primary dns) will pop up when I trouble shoot the connection.

any suggestions that can resolve this connection?