Assuming that Dean is nominated, I believe he will have to choose an anti-war running mate. Using this hypothesis the two most obvious choices would be Wes Clark and Bob Graham. Both Clark and Graham have the same "we should have gone after the terrorist groups, not Iraq" message. Obviously Clark is more articulate, but Graham has the advantage of being from Florida. I am not sure who would be the better running mate.
BTW, can anyone think of some good running mate possibilities other than Clark of Graham that most people haven't thought of? In 2000 I thought John Glenn would have been the perfect running mate, but I must have been the only one. This year I cannot think of many viable "dark horse" possibilies.