Each reason was total and complete BS. They knew that Iraq wasn't an imminent threat. They knew that whatever designs Saddam had with respect to WMD's, he couldn't effectuate them. Nothing he did justified what followed. Does your opinion differ? I'm sure it does.
As for oil, perhaps you want to think about this, it was written pre-war...
http://usgovinfo.about.com/library/weekly/aa021601c.htm
Now, ask yourself what it would have cost *us* if oil started being traded in Euros. And ask yourself if we were going to let this guy who we propped up to fight our proxy war with Iran, bankrupt this country by forcing us to trade oil in Euros?
Interestingly, I don't think protection of the oil supply is an illegitimate reason to go to war. But it should have been said instead of all the changing and evolving excuses. It's like, well, I was late, I was busy, the dog ate my homework