You can't go wrong with a suit. I do a lot of interviewing for entry level office positions, and I am always more inclined to hire a candidate who is wearing a blazer/jacket/suit. When an interviewee shows up with just a blouse or a shirt and tie, I wonder if he or she understands what it means to "put your best foot forward." I haven't seen much of a correlation between interview attire and job performance, but I will admit to "interviewer bias."
Oh, and be sure send a thank you note too!
Hope that you get the job, if you want it.
