Hmm..ok, are there any other WiFi routers in the near by vacinity?
What OSX version are you using?
I would do this, Factory reset the router using the back button or from the routers web page via LAN cable under Tools/System.
Turn off the Wifi on the Laptop.
Use the LAN cable from the LT to the Router to log back in set set up the WiFi for single mode G with out any security for now. Set a SSID name. Channel and Width should be set for auto.
Make sure you get Internet over the wired connection. Then disconnect the cable and turn on Wifi on the LT. See if the WiFi will auto connect, it should or use the drop down to connect to the SSID you set up.