No WWII?

Background
In 1939, Adolf Hitler ignored the orders of British Prime Minister Neville Chamberlain and invaded Poland, leading to the declaration of war on Germany by Britain. However, in my version of reality, Hitler instead chose not to invade Poland, and instead turned his attentions to the African colonies the Germans had lost in the Treaty of Versailles. My question is, what would the world have been like in the 75 years since that fateful day in September '39?

What I will explore
I will explore many of the world's major countries, and how their future has changed through one incident. I will also explore the change of political beliefs since 1939, and how events in the world came to shape those beliefs. I will also explore the few occasions in 'peace time' where war was fought out, and will finally look at the major world leaders over the last 75 years and explore how their lives have changed as a result of there being World War Two.