I don't know whether your modem utilises UPnp, but just in case it doesn't you might be advised to forward a port. The most important thing here is to set up a static ip 1st & get it right or else it won't work!
The steps:
1. Set up a static ip
2. Forward
port 6346 using these instructions:
http://www.portforward.com/efficient/5200.htm & the instructions for setting up a static ip are included!
3. Within LW:
Manual port forward instructions & sample image & 2 posts after that.
By the way: Did you configure your firewall so it allows LW full access (advisable not to have 2 active firewalls b/c they can interfere with each other);
Firewall configuration instructions (click on link) (Win XP has its own firewall. To disable it; go to the control panel, double click on Windoze Firewall, check the disable box) But you should have at least one active firewall for your own protection.
Get a hold of these recommended utilities which work safely with LW & do not give improper readings!:
ad-ware (FREE) Spybot - Search & Destroy (FREE) Peerguardian (FREE)