Well, Russia was really our ally in the beginning. Hitler was clever to sign a non-agression pact with Stalin, to divide Poland into half, each for Germany and Russia. So that meant Hitler would not have to fight two wars, one on the Western Front and one of the Eastern Front. Hitler could just focus his energy to invade western countries. When he invaded Russian Poland, Stalin knew he was betrayed, so the western powers helped him.
Stalin was a very powerful leader, you're right, Stevey... He killed millions of his own people in pogroms. This continued, even after WWII. A very sad part of Russian history... Maybe you are right, Stevey, Saddam is more similar to Stalin than Hitler.
Remember, USA did not join the WWII right away. We refused to help England and France in the first place. WWII began in 1939, and Pearl Harbour was bombed in Dec 1941. Two years, we did not give any military support to England at all, except to send supplies. When Japan declared war with USA, Hitler declared war with us too. Thus his fate was sealed.