There are really big differences between Hussein and Hitler. Hitler had the strongest army in the world, the most advanced tactics, and the largest industrial infrastructure in Europe. Saddam has an army which was demolished by America when it was at full strength, and his infrastructure has been bombed and embargoed into oblivion. Saddam has not attacked any nation since Kuwait; if we ever had the right to oust him, it was then. Hitler was annexing countries at an increasing rate. Leaving Hussein alone isn't appeasement, it's letting the wasps nest alone because it's not near anything that you need to get at. Finally, the only way Saddam will use WMD's is if he is invaded. Using them guarantees his ouster, but there's no reason not to if he's already doomed, and his targets conveniently enter the 700 mile range of his missiles.