You need to use the internal IP address when people connect who are on your network. You can get this by typing in command prompt: 'ipconfig' and take the 196.*.*.* number that comes after the section marked 'IPv4'. When it comes to your external IP address, used when people from the outside want to connect, you need to port forward your router. This only needs to be done on the port the Minecraft server is running on, which in most cases will be '25565', and you should forward it to the internal IP address of the computer you are using to host the server. Just googlefu 'port forwarding tutorial' if you're unsure of how to do it. This means that players should now be able to connect with your external IP address, which you can find by searching for 'whats my ip?'.

Best of luck to you. It's a shame that OP couldn't answer your question sooner.

Well frankly. I have no idea. I can't help you, sorry. I use server hosting. It's much easier. I use servercraft, wel I did until I moved to fragnet, servercraft is awful, don't go near it.

But then they will lose aprox 70% of the communety not including the griefers!
The griefers will only be there to grief so they will leave after a while too.