I really don't think that the voters still up for grabs care at all about what Bush did or didn't do 35 years ago.
Maybe 4 years ago, when Bush was an unknown commodity. But now they have seen him in action for the past four years and know very well what to expect from him.
For Kerry, his behavior 35 years ago is more relevant, since voters don't have a lot of information about him, and he has made his Viet Nam career the cornerstone of his campaign.
I say through Viet Nam out of bothe sides. Even Kerry's Anti-US/Pro-Commie post war activities. Then look at Bush's 3.5 years as Commander in Chief and Kerry's 20 year senate record.
That is a loss for Kery as well. Basically Kerry is a loser in any match up.