I live very very close to Champaign so I had to get in on this. I would pretty much agree with what's been said about the IL fans. If they beat you, you'll prolly never hear the end of it even though they've been terrible since the beginning of time. But for the most part there really is no football following. The Husker fans would have a good chance of outnumbering the Illini fans in Champaign and the kids really only care about getting drunk before the game.
I can't really speak for WI fans because I've never been to a game but I have a good friend that lives up there and those folks do drink a lot. I can't really blame em though if I had to deal with that weather I would drink a lot too.