The recent thread on how dropping the A-Bomb on japan may have saved many lives got me thinking, did the development and use of the atomic bomb also prevent the "cold war" from becoming a "hot war"?

In school we are taught about the mutually assured destruction princible which is fairly self explanatory. Basically it says if one country attacked another country the ensuing war would end up destroying both countries, and both countries know it.

So my question is if the nuclear bomb had never been invented and the U.S and USSR had spent there billions of dollars on more conventional weapons instead of nucleur one's, would they still have felt the same threat from the other country? How likely would it be for the 2 countrys to abandon the Mutually Assured Destruction princible and go to war with each other?

Personally I think that the threat of nuclear weapons kept the cold war from becoming a real war. Anyone else have thoughts on the matter?