Ach, voted Obama when I tried to vote Feingold.
Anyway, the economy will ITTL's 2008 will probably be worse, since Bush will probably not be nearly as proactive in responding to the early stages of the economic downturn. We'd also probably still be stuck in Iraq with no way out, instead of three months from a total withdrawal, which will make us even more war-weary and anti-Republican. That means that any reasonably coherent and scandal-free Democrat is virtually guaranteed a victory. Hillary would remind people of the good days they had under Bill, but it's the extremes of the parties that usually turn out in the greatest numbers, and a few early victories could be enough to put Feingold in the nomination. Also, historically, the Dems rarely elect the initial front-runner; look at Carter, look at Clinton, look at Kerry himself. The Republicans will likely nominate McCain as IOTL, because he was the last runner-up and that's how the Republicans work. Obama would likely make a strong showing among black voters if he ran, but I don't think he can win any states. Maybe a few Southern states, but that's it.
The general will see a massive Democratic landslide, instead of OTL's sqeaker. The Republicans will be blamed for the probably-worse economy and the Iraq War, and they will suffer at all levels. Feingold/whoever probably gets at least 350 EVs.