Zafar, your experience is amazing man! You inspire me to have the same goal to run a marathon on all continents. The Antartica race sounds amazing, I really would like to do that race some day.
What is your next goal? You should maybe try 50 marathons in 50 states!? Be careful what you decide to do - it could be a big commitment!
You should post your details of your 5 years goal running all those races in a 'Blog' posting so other's can read it on your page.