If you are running any server applications through a router you need to understand something.
A router takes your IP address and splits it up into a bunch of local ip's but in whole they are all still the same IP address. When other computers around the world look for your pc they need your ip assigned by your ISP not your router so put the one you got from whatsmyip.org but then realize your computers under a router cannot be seen to the outside world on my router however (possibly on yours too) one ip address is seen to the outside world this is 192.168.1.100 your may be different just make sure the end is .100 and then people outside can connect to you.
HOW TO SET YOUR IP
The easiest way is to set a static ip
go to your internet and go to
http://192.168.1.1 this will direct you to your routers configuration setup most likely the user is admin and the pass is admin by default.
Now you need to do some searching cause every router is different your router (most likely cause otherwise you would figure out how to set your ip without reading this.) right now is assigning your local ip through DHCP you need to find something in a section about DHCP that says starting number and change it to .101 it should be set to .100 by default this will allow .100 to be assigned dynamically
now go to start>setting>networkconnections
IF YOU CANT GET TO NETWORK CONNECTIONS THAT WAY ITS IN YOUR CONTROL PANEL
now right click the internet connection you use and click properties go to INTERNET PROTOCAL [IP/TCP] click it once then click properties button
now go back and click your internet connection again in your network connections but this time dont click properties instead click the support tab then details now go back to the ip/tcp configuration click use the following ip button put in
IP ADDRESS: 192.168.1.100
SUBNET ADDRESS: 255.255.255.0
DEFAULT GATEWAY:192.168.1.1
PREFERRED DNS: PUT THE DNS ON YOUR IP DETAILS
ALTERNATE DNS: PUT THE DNS ON YOUR IP DETAILS
after you click ok your ip should change to 192.168.1.100 and should stay there forever so you will always be the only computer on your network noticed from the outside :)
Hope this helps