Those who compare Iraq in 2003 with Iran in 2012 simply have no slightest sense of military world.Iran's strategy in war with that of Iraq,are 2 worlds apart.Iraqi army practically did not fight any of U.S forces and many of them surrendered in first 3 days.
In southern parts of Iraq,near Basra, where some local Shias resisted U.S invasion, it took U.S army 2 weeks to capture those areas,and those who were fighting were not even trained soldiers.
In conventional military,Iran is no match for U.S,no country in the world is,not even China and Russia.But military strategic is based on deterrence not offensive and most of it is purely asymmetric. Iran has one of the largest asymmetric warfare and armies in the world,we all know how that ends for U.S.. Vietnam is a very good example.
Iran's strategy is not to win a war against U.S, it's preventing them from launching an attack which has been successful by not,and then, inflicting most damage to U.S and those who help it in war.
About Arabs helping U.S in a war, it's pure nonsense. They simply don't have balls.One missile in each of their cities, their oil facilities destroyed and they simply go back to what their ancestors did in deserts.Arabs are not stupid to do such thing.
At the end, I say there will be no war, mark my word.It's in no one's interest.