I forgot also to ask how a predominantly budhist country with apparently a not so insignificant Catholic minority was taken over by a "godless" communist regime.

I don't think the U.S. should have been involved in Vietnam after the French decided to throw in the towel but considering what happened after the Soviet Revolution and the Peoples Revolution of China I can see where some might have believed they were keeping a great deal of the native population from being slaughtered simply because of the fact that they lived in and worked for the French.