|There is a difference between port opening and port forwarding, they are two completely different things.|
Port forwarding doesn't open the port to the outside world. It just instructs the router to forward any packets it receives on that port to be directed to a particular computer. If there is a software Firewall like Mcafee then it wont go anywhere.
Port opening is done via a firewall. Most routers these days have a built in firewall which will need to be configured to allow packets through on the selected port.
Some router will allow you to receive packets on one port via an open port and forward it onto the computer via another port. Port address translation similar to Network Address Translation.