JJ2 only uses ports 10052-10054 TCP and 10052 UDP. If you are running a list server, you need ports 10052-10057 TCP, and probably some UDP but I'm not sure.

Let me ask: do you have a complete wireless network, or is there a combination of wired and wireless? If the JJ2 computer is wireless, what is managing the connection? Windows XP has built-in wireless management, but it can be disabled and let the wireless adapter driver take over. Check the wireless settings (either through Windows XP or through the wireless driver) and make sure it isn't blocking anything.

Also try unchecking the single "Deny" rule, and see what happens.

Do some experiments, like running some sort of server behind your network and see if it works. For me, it turns out that the TCP forwarding works fine but the UDP forwarding doesn't seem to work properly (meaning JJ2 has trouble with internet play).