Saddam became a "tyrant that needed to go" in the Middle East after we stopped propping him up in his war with Iran in the 80's. How many billions did we give him when he was our "ally"?
"Destabilizing force?" He was left in power after Desert Storm because, according to the Republicans, Iraq served as a "buffer" between Iran and Israel. When did this doctrine change? After Hussein stopped taking dollars for oil. Our special interests could not let that happen. Check this article, and check the date:
http://www.time.com/time/magazine/article/0,9171,998512,00.html
I really don't expect you to look into it, because your little fantasies about the United States government freeing people from oppression are much more soothing.
I am sure the people of Eastern Europe, all of Europe after WWII, Japan, and other countries would disagree with you.
Foreign policy is a difficult business, and an enemy at one point might be a friend at another time. It is simply a universal truth throughout history. Isolationism is not the answer, except to Paulites.