Various reasons...
To remove a threat that was funding Hamas and other Muslim terrorists and awarding the families of suicide bombers attacking Israel up to $25,000
To remove a regime that when given the chance (I say when because the UN would have definitely relented) to work again without the UN sanctions, would have began to produce WMDs according to the Key Findings report by the head weapons inspector on WMDs
To remove an individual obviously harboring terrorists and giving them amnesty and protection from outside forces through diplomatic loop-holes... if you wish to see the evidence yourself, go to
www.husseinandterror.com/ To help liberate an oppressed people and establishing a foothold of democracy in a Islamo-Facist sector of the world, hopefully creating a point of entrance for western ideals, and furthermore, the increased VOLUNTARY westernization of a region so that they will no longer be as hostile towards westerners.