As I see it, Italy didn't contribute much. They bangled Egypt, they couldn't even beat the French forces when they declared war just as Paris fell, and they totally got buttkicked in Greece. It only forced Germany to spread its forces to other theatres that could have been avoided.
So what Italy remained neutral and continued to bugger the Allies (after Aithiopia/Abysinia and stuff) while Germany concentrated on Europe, Scandinavia and Barbarossa. Perhaps Germany could have taken Sweden as well as Norway and be better able to support Finland. Also what if they could now afford the time to procure Turkey's allegiance, or invade it and then Iraq and Caucasus?