I have this case and for the moment i didnt put fans on the top, but the other fans I have them positioned as you are showing. System is 1 year old and i never get above 60 degrees cpu (i7 930 2.8ghz with N520 coolermaster) and gpu never over 65deg. (hd5870).
I have been thinking to put fans on top and i think the most effective would be to have:
//// rear //// middl //// front ////
//// push out //// push out //// push in////
//// cpu //// ram ///
i hope this plan was clear