My ISP updated the firmware of my router which disabled/removed DDNS. So I gave Teamviewer a try. Its great! It just works, no account required and its free! I have even started to use it using my Android phone. It's often said if things sound too good to be true then they usually are. Teamviewer is an exception, as I was told many times.
Thanks for the help guys, and for anyone reading this post because they are wriggling around with IP addresses, DDNS and Windows Remote Desktop just save yourself a few hours and install Teamviewer!