Alright, I'm not going to hyper-ventilate before the debate this time. Andrew Sullivan thinks that Cheney will crush Edwards. I'm not so sure. I can imagine both parties legitimately claiming victory after this one, and the final decision on "who won" coming down to those who really count in this election: The viewers and voters. Just kidding. This one will come down to the spin wars. Cheney is very, very good at inspiring the fear of God in people. He makes even absurd threats sound credible, and he has actual legitimate threats to work with in this debate. So he can go the "tough realist" route, and gain applause and laudations from the Conservative blogosphere. Edwards, meanwhile, still has a good reputation and vibe amongst voters, and assuming he goes on the attack, he'll continue the Democrats' ever-present quest for credibilty, hopefully taking some swing voters along the way. One of Edwards' strengths is that he can sound nice even when he's ripping someone to shreds, in contrast to the gruff Cheney (both of these tactics, incidentally, have their merits). Since the speakers have such disparate speaking styles, both sides will play up their candidate's strength in the debate, and it will be up to the media to pick the storyline and thus anoint the winner. This isn't to say it's impossible for one of them to have a clear victory tonight, I just don't think it's as likely.
Ironically, one thing is certain about this debate: It won't matter. So don't stress!