AFAICT, the thing that "saved" Europe wasn't so much the help of the Americans, as it was the german east front. So much of the Nazis resources and manpower went there (93%-95% according to some articles), aswell as russian resources to combat it, weaking them aswell. So, in a sense, you could say the russians actually "saved" Europe from Nazi-germany. I can't even imagine how much worse the ill-planned and ill-executed west front could have ended if it weren't for the east front.
But on the other hand, you might argue that the support of the americans saved us from a russian onslaught though. That, and the finns!