While I like Ron Paul's isolationist views, let's be realistic here. AIPAC and Congress won't allow US foreign policy to change that dramatically.
On the other hand, Republicans would certainly go along with him in effectively destroying health care for the poor and needy (see the analysis of Ron Paul's Health Care policy by Mother Jones here
). In a period where US citizens are too frequently falling out of the middle class because of medical costs and bankruptcies associated with unemployment, I find that a more important reason not to vote for Ron Paul.