Saddam and Al-Queda did have much in common they were both from the sunni tribe. However the Sunni we called Saddam had in past years attacked other Sunni nations in an attempt to extend his power. We (the US) probably got involved as a favor to our supposed allies namely Kuwait and Suadi Arabia (both sunni majority) in order to protect them from further agression. But we needed an excuse to send our troops to fight someone elses battle. Americans had to made think that they too were threatened before we would agree to send our troops to remove the 'trouble maker' Saddam.
Saddam wouldn't dare start another major offensive against shiite nations it was stalemate especially since he was a minority sunni in his own country. I fiigure he wanted to be the leader of a greater sunni nation before taking on the shiite nations and to establish a unified islamic nation. Under his leadership of course

I know Im rambling.
"But those who believe the U.S. presence is the catalyst only choose to believe a particular political agenda rather than historical facts known for centuries. Sadly neither side of the U.S. presence theory are correct. The belief that any strength of force moderated by the ideals of democracy and religious freedom tempered by separation of church and state can overcome this struggle is naive to the extreme."
The only reason Iraq was held together for the last part of the 20th century was the fact that Saddam Hussein was not limited by any liberal moderation of his actions -- he simply tortured and killed anyone who did not go along with his particular version of the Baath party. And the kind of torture we are talking about here is not the pacifist's definition of "making someone feel uncomfortable". Indeed those who survived Saddam's (more likely his son Qusay's) torture, would look upon the liberalist definition of torture as laughable, saying in effect, "Feeling just a little uncomfortable would have been a god-send.""
Which means we are stuck in the middle of a messy tribal war with little chance of leaving the area in peace.