Well I'm pretty sure they don't admit anyone that they don't interview so it is a good sign in that respect. Congrats and don't sweat it... You're an intelligent woman and speak well... Just be yourself and you'll be fine. Good luck!
Thanks all for the motivation and good counsel - the community here is definitely one of the best parts of this program. @"Nicole Hopkins" - Believe me, I would love to! Northwestern is one of my top target schools.