Daggett may pull some anti-Corzine vote, but he seems to be more of a Lefty, so he's probably going to do as much damage to Corzine as he will to Christie, in pulling 'Progressive' votes that Christie would have had no chance in Hell of ever winning over to his side anyway. These voters would normally default to the Dems, holding their noses and voting for Corzine despite having no use for him, but mainly just to keep Christie out, in much the same way many of us did for McCain a year ago.
I also think that polling as to third party candidates is especially unreliable. It's just a gut feeling, but I don't think the people who say they are going third party follow through in anywhere near the percentage the two leading parties' adherents do. It's one thing to 'Make a statement' by telling a pollster you're going to vote third party when you are tracked down and questioned, it's another thing entirely to blow an hour or more of your day to leave the house or work and fight traffic to vote when you know in advance that the guy you support is definitely not going to win or even come in second.