Nader is not going to be much of a factor just as he was not much of a factor in 2004 because the Democrat party is doing their best to keep him off the ballot in most states.
As for Hillary hurting Obama, the sad truth is that Obama has so much going for him she is mostly hurting herself right now.
Those blue-collar Democrat voters who oppose Obama won't go for McCain who is for open borders and a never-ending war in Iraq.
Chances are they will stay home, while Obamaniacs will turn out in droves come November.
Hillary is just holding on to get to the convention with the hope of playing insider politics and win the nomination by convincing the super-delegates that she is most mainstream candidate.