US military budget in 2005 alone was $421 Billion dollars plus another $75 Billion for Iran/Afghanistan operations.
Iran's military budget in 2005 was $4.9 Billion dollars.
This does not take into account inventory left over from previous years, nor does it take into account qualitative differences in the equipment OR the personnel. It also does not take into account the cooperation (public or covert) of some other nations in the area, who are not exactly best friends with Iran. (I can think of at least one such neighbor with a very capable military.)
If the US does decide to move against Iran, it is going to be an unholy mess and the Iranians are going to quickly come out very second best.
The politicians on both sides are stupid - the US has a one-track mind right now about Iran, and Iran is convinced that the US is about to attack, so they keep on yelling about how tough they are, and trying to prove it by continually tugging on Superman's cape - which is a mistake on their part.
This is going to be a self-fulfilling prophecy - Iran will lose the fight, big time, everyone will lose the war.
I don't want to think what a barrel of oil will cost . . .
Best Regards,
Echo Mike