What was the impact of the Nazi-Soviet Nonagression Pact?

The impact of the Nazi-Soviet Nonaggression Pact had
little impact other than the early destruction of Poland. Its purpose was to prevent
another two front war as had been the case in World War I. The Pact provided that
Germany and the Soviet Union would remain neutral toward each other in the event of war
with a third party; but contained a secret proviso that the two nations would have
separate spheres of influence between then in Eastern Europe. Germany would control
Western Poland and Lithuania and the Soviets would control Eastern Poland, Romania,
Finland, Estonia and Latvia. At the time the Germans executed Operation Fall Weiss, the
invasion of Poland, Soviet Tanks entered Polish territory on the eastern
front.

Needless to say, the Germans at Hitler's behest
violated the pact by invading the Soviet Union under Operation Barbarossa. Hitler
considered the entire communist system to be bankrupt, and commented
once

 You only
have to kick in the door and the whole rotten structure will come crashing
down.

The invasion was of
course one of Hitler's major mistakes. Had he abided by the Pact, the course and outcome
of the war might have been entirely different.