1. Make sure your D-Link has UPnP enabled; Steps to Enable UPnP for D-Link DI-614+
If you do manual port forward, you must first set up a static ip or else the process won't work; PortForward.com - Free Help Setting up Your Router or Firewall (check far left column down bottom.) One of these techniques of upnp or port forward should work.

2. Make sure you made exceptions for LW in your XP firewall; Firewall configuration instructions (click on link). Security updates are known to sometimes set the firewall back to default settings.