Windows Security Essentials is just an Antivirus/Anti Spyware program, no network filtering so try turning off Windows Firewall just in case.
As for the IP Address to use for port forwarding, you'll want to do this on your AHP PC:
http://compnetworking.about.com/cs/windowsnetworkin1/ht/findaddrwinxp.htm
Those instructions will let you know what your computer's internal network IP address is, this is the one the router has assigned to it.
OK I followed those instructions and it showed me my internal network IP address, which is the one I have been using so far when trying to configure port forwarding in my router. I also turned off Windows firewall, but
I still can't connect from a remote computer that's on a different network.
I
can connect thru MyHouse between 2 computers that are in my own house,
which are both using the same router. And it doesn't seem to matter if Windows Firewall is on or not.
But even after port forwarding ports 80,443,8080&8888 in the router, when I go to a port tester website it shows that these ports
refuse a connection, which I don't understand.
If you could help me out with this it would be really great, as I'm at my wits end.