I've been to both places.
Kirkwoods has a nice outdoor area with tv's but no sound. Also, one half the bar is setup for Indiana fans which it looks like they have a 6pm game this week too. This place gets really crowded, so if you want a seat get there really early.
Birds Nest is a good place to watch the game and like haymarkethomer stated it is a smaller place. You will have an easier time getting a seat at this place compared to Kirkwoods.
A new place I went to for the first game is called Beckett's Public House, http://beckettschicago.com/. Good size bar and they too play the Husker fight song and have some pretty good beer prices. The next tv game I can make it to I will be heading back to this place.