Many thanks for the replies, I've got it sorted Now
Amazingly the problem was with the router (Buffalo Nfiniti), although the port was open it wasn't allowing connection through it for some reason, my brother updated to a newer version of Buffalo firmware and still the problem persisted.
Then he managed to get hold of a Custom Firmware, and it worked.
So I had set everything up correctly after all.
I must say that the remote viewing and playback really is a useful tool. Very Pleased. Also the custom firmware for the router is much better than the standard, and is laid out much better.