I don't know if this has been mentioned already... Go see "The Boys from Brazil" staring Gregory Peck and Laurence Olivier.
If I wanted to change history - and if I had that ability - I'd choose a far better, cleaner and more certain method than killing a baby.
World War II didn't happen purely because of Hitler but because of massive outbreaks of nationalism, dissatisfaction with post-war recessions and frequent humiliating invasions by France. Although you may prevent the holocaust it might not have prevented the war and its hardly a clean way to manipulate events.
I'd prefer a way of garanteeing Germany's peaceful restructuring and creating an economy and political situation with stability, where Hitler and the nationalists would have been imprisoned by a jury of their peers at a young age for being a bunch of racist fruitbaskets.