John Kerry Should Thank Howard Dean Profusely
By claiming the left wing of the Democratic Party as his own, Dean created space towards the center for Kerry to emerge as a "moderate" alternative. Without Dean in the race, Kerry would've been the most liberal viable candidate; and centrist support would've drifted to the candidate who best positioned himself as the moderate alternative to that liberal Kerry.
I don't know if the voter perception of Kerry as a moderate will hold through the general election. Unfortunately, most of the swing voters and Reagan Democrats probably aren't paying enough ettention right now to form a lasting impression of Kerry before the Bush war machine gets cranked up.
This could've all been different. If Dean had emphasized his moderate record as Governor rather than running almost solely on the war (until just before the election), he might've actually emerged as the moderate alternative, rather than as the liberal sacrificial lamb.