I think It would be a much bigger win for the GOP. Sanford is a much better candidate than Bush, He dosent have to worry about his family or being involved in the Iraq War. He is also a much better speaker than Bush.
Edwards is also not as god as kerry, He has a fraction of the experience, Many people think he is fake and he would lose some of the NE and would not help at all in the south.
It is ridiculous to have Oregon, Maine, or Michigan going GOP in 2008. Here's a more realistic map:
And a best case scenario for Sanford: