We beat NW at home by two TDs. My prediction. Not overly worried about them.
I'm watching the 2012 game again on DVR the last couple of days. If we don't give them the ball on our side of the field twice in the first quarter due to our own utter stupidity, we win that game in a cakewalk. If we had only figured out how to cover that stupid crossing route in 2011 we win that game, too (and if Rex doesn't fumble at the five yard line).
Northwestern is supposed to be better this year than recent years. I say great - they're going to need it. If our defense is even only as good as the last two years, and if our offense doesn't utterly crap the bed again, I think your prediction of a two-score win is pretty accurate.