There wasn't one Obama voter from 2008 who wouldn't have also voted for those two. There's no reason why West Virginia, Missouri, or Arkansas (and perhaps Montana) shouldn't have gone to the Democrats. These states tend to vote for the Democrat Party nominee with the conditions at play in 2008 and Obama somehow managed to lose these states by 20 (with the exception of Montana) when Clinton and a faithful Edwards would have won everywhere else that Obama won.
I would never have voted for Edwards; had he been nominated in either '04 or '08, I would have stayed home. Even when he was getting play in the 2004 primaries, the only reason I could fathom that he ever seemed to be running was his own narcissism ("This is a great country, where a man whose daddy worked in a mill has a chance to become president."). Plus, the way he conducted himself in the VP debate against Cheney in 2004 was, I thought, disgraceful. Obama lost Montana (which has voted for a Democrat only once since '64 and twice since '48, largely because of Perot in '92) very narrowly and Missouri by a hair. And there is a very distinct reason why he lost West Virginia and Arkansas in a year when an alternative white Democrat may not have.