I was going to write about this but the very sharp ( to use a Brad De Longism) Allan Behm has done this at the Lowy Institute.has done this superbly.
A few points.
We knew Hussein had no weapons of mass destruction. Any chemical weapons from the Gulf war were degraded and there were no new chemical weapons. We know this from Rod Barton's book. This didn't stop John Howard saying the opposite one day after meeting with him!
The idea Hussein had any actual or potential nuclear weapons was simply absurd.
Put it another way. If you believe he did have weapons of mass destruction why would you put your own soldiers in harms way?
Iran still possessed Iraq's best jet fighters, they did not have enough spares to service all their tanks and their infantry were made to look second rate in the Gulf war.
If Hussein was gotten rid of because he was a bad man then why they simply stop with Hussein. There were and are still plenty of those men around the world.
At best the Leaders who declared war on Iraq had poor judgement
Rod Barton on Chilcut and OZ