Right, I'm going to stick my neck out.
I'm going to vote for Thor Hushovd.
Boonen is not quite on form this year, and there are conflicts within his team regarding Bettini. Bettini himself has taken a few tumbles recently and doesn't really seem to be himself. Petacchi is no good when the competition is as fierce as this, and he's also no climber which takes him out of the running. Zabel is perhaps a bit too old, and the Milram team will be rallying behind Petacchi - I still think he'll be top three, though. Pozzato will be watched by QuickStep, they don't want one of their defectors to win. Freire is a possibility too, but I don't like him as much as Thor!
In fact, I'll predict the top three:
(really, though, a load of Italian no-marks will take up the whole top ten!)