There seem to be about a million ways to pronounce the President of Iran's name, but I'm pretty sure there's just one right way. The key is to recognize that the name is really two words crammed together: "Ahmadi" and "Nejad". Before he was in the news so much, the name was often spelled "Ahmadi-Nejad" or "Ahmadi Nejad", which makes it more easily spoken by westerners.
The first part, "Ahmadi" is the most significant because it identifies the President as a follower of Mirza Ghulam Ahmad. (Not sure if he actually believes that stuff, or if it's just in his name.) I think the second part, "Nejad", is a town or region in Iran, but I'm not sure.
So I believe the correct pronunciation is: ah-MAH-di-neh-JAHD.