Connectivity Problem with a Secured Wireless Network

I have a Linksys WRK54G network setup with WPA-PSK security.

I have a Dell laptop running XP that has no problem connecting to the network with the the security password. I have another Dell laptop running XP that sees the network but is unsuccessful at connecting with the same security password. When I turn off the network security at the router the laptop has no problem with connecting.

Anyone have any ideas what the problem might be? I don’t want to run the network without security being turned on.