Polls showing the opinion of the Iraqi people. The fact that the Iraqi government does want american soldiers tells you they are not democratic, or not democratic enough. The US would never implement a government in Iraq that throws them out. So this is only natural.
Yes, 9/11 and Iraq had nothing to do with this. US government admitted this. But there were quite some things the US government said that implied or suggested a connection. The result was that a large part of Fox viewers thought that this was the truth. Also, american people really feared Iraq, while their military buget was 1/3 that of Kuwait. Now look at the map and compare the sizes. Iraq was by far the weakest military power in the region. And it showed. The Iraqi military collapsed almost instantly.
Now religious extremists, people Hussain would have tortured to death the moment they entered area he controlled, plus some baathists fight an insurgency. And they can do so because a minority, but a significant part, supports violence against american people. Also, there is a power struggle between shi'ite ans sunnis. Al Quada attacks shi'ite mosques. This is why Hezbollah hates Al Quada and this is why they do not use suicide attacks like Hamas. It's against their ideology.
Shi'ite: Hezbollah, Iran, Iraq.
Sunni: Al Quada, Palestine, Saudi Arabia, Baath&Hussain, Hamas