Let's compare the experience level in high political office:
Dean: 11 years as Governor
Clark: no political experience
Vilsack: 4 years as governor
Edwards: almost 6 years as Senator
Gephardt is the only other serious possibility that has more experience (and most of his career was as an unknown Representative).
Add to the fact that Dean is a licensed doctor, agrees with Kerry on almost every issue, and is extremely popular with the liberal base, you have the best qualified VP candidate.
To hell with the idea that the only "real" Americans live in the midwest. New Englanders are people too!