I think the difference between Dean and Edwards is HUGE. The far leftists will view Edwards as wuss boy centrist, and the Edwards supporters will view Dean as a loon. Edwards will attract the centrist, blue dog Dems, while Dean will get the wacko leftist rah rah crowd.
I think it would definitely be best to have Kerry over Edwards. If Kerry, or Dean for that matter, gets the nomination, Bush won't have to spend a DIME in the South. Not a DIME.
That leaves hella money to poach away at swing states.