Kicky has a valid point.
Regardless of how we feel about the justification that brought us there (I opposed it), NOW we are stuck there, and their problems have become our problems.
If we pull the troops out, religious extremists will most likely fill the vacuum of power, and use the strong anti-american sentiment to develop a following that could lead to who-knows-what.
In the interests of our country and the supposed "democracy" that we want to give them, we just have to manipulate the political system there. Its an unfortunate choice to have to make, but if thats what we want, thats what we gotta do.
As for troops, they simply have to stay there for a looooong time (at leaset until the UN or other nations can fill our shoes). While it can be said that we are occupying that nation, they are providing some semblance of order. In fact, to cut down on all these attacks on the troops, we just may need more soldiers there. A LOT more soldiers. No way are 150,000 troops going to keep order in a nation of that size.
Regardless of whatever choice we make now, both the United States AND Iraq are f*cked. We kicked the hornets nest and we'll be feeling the stings for generations to come.