Hussain is much more evil.
At the time England went to war with Hitler's Germany, was more or less known about Nazi atrocities than is known about Sadam Hussain's atrocities?
The answer is no. We are told that the allies were shocked at the extent of Hitler's evil when the war was over and the Truth came out. Add to that, the fact that most of Hitlers atrocities probably didn't even occur until after England declared war on Germany.
So you are in a sense saying, England was wrong to attack Hitler. If fact, taken to its conclusion one might argue that England by declaring war on Hitler, was a major cause of Hitler's Final solution.
We are fighting the same enemy now as we did then: Totalitarianism.
Scott