@ WAG0376,
If you haven't already, turn off your xp firewall. Not advisable to have 2 firewalls running at the same time.
Your router has a nat firewall in it. you'll need to set it for upnp or forward a port. I've read it's better to forward a port with your type of router.
First step is to set up a static ip(very important, won't work without it):
How to set up a static IP address on a Windows XP computer.
Then forward the port:
Port Forwarding for the Dlink DI-524
Let us know how it goes.