Don't use the Windows firewall with the Norton firewall...they'll conflict with each other. Turn off the Win firewall & configure Norton to allow LW.
PortForward.com - Free Help Setting up Your Router or Firewall

Update your Java. Use the JRE offline installer & remove your current Java version before you install this one.
Archive: Download Java 2 Platform Standard Edition (J2SE) 5.0 Update 11

Your router has a firewall. Try port forwarding, the instructions are here.
Port Forwarding for the Linksys WRT54G
Don't forget to set up a static IP address first (if you set up port forwarding for more than 1 computer, each computer will need a separate static IP). LW's listening port, port in the 'manual port forward' box & port forwarded within a router all have to be the same number.

See how you go with that