Making the right decision on Iran

I read here and there in the blogosphere about how very difficult it was in 2003 to decide whether the Iraq War was right or not.
Actually, I don't think it was a hard decision at all.
The war on Iraq was based on a unjustified doctrine of preemptive war. It was a war of choice on a nation which had not attacked either the United States or Britain or their allies. And it was a war which was not authorized or supported by any recognized group of nations, like the UN or NATO.
Therefore, of course it was wrong.
Now we're reading the same hysterical arguments promoting war with Iran. This would be just as illegal, immoral and wrong as the Iraq War was. And given the record so far of the Bush administration -- which consistently screws up because it hires incompetent Republican hacks -- a war with Iran would likely be just as incompetently executed.