If the tickets flipped: Biden/Obama Vs. Palin/McCain

[True Democrat]

Assuming that Palin has a slightly better performance as a Presidential candidate (otherwise, how would she have gotten the nomination?):

391-147

I see Palin's vote declining a lot more in states that Obama won than in states that McCain won, though it would decline enough overall to flip some McCain states.  The one area, Applachia, where Biden would have performed better than McCain is also prime Palin country, IMO, which is why Biden doesn't pick up too many electoral votes.