Here’s my 2 cents:
The interview is not (usually) resume based. The interview is a way of finding out more about you as a person that was not in your application. Questions will most likely be about professional experiences, how you reacted to them, your personal and professional goals, reasons for choosing this specific school, plans for getting involved at the school, plans after you graduate, etc. One of the traits that business schools look for is leadership potential and/or skills, and how you demonstrated that in your professional career. There is also a focus on soft-skills and communication, and you might get questions that present you with a certain scenario and ask you how you’d react in the given scenario, or be asked to relate a scenario based on a specific problem type in your professional experience.
Just be yourself. Be honest. Be sincere. Don’t be afraid to share your weaknesses, but do show how your strengths will help you and the other students enrich their MBA experience. Have a clear understanding of why you want to pursue an MBA, why you want to attend this specific school, what you want to do at the school, what you plan to do after your MBA and what steps you have taken to prepare for those goals.
Remember that if you’ve received an interview invitation it means they already find something they like about you, so don’t be too nervous.
From experience, your chances are not 50/50 in an interview. Business schools interview well over twice as many candidates as they admit, especially in this economy where the average increase in the applicant pool has been about 15-20% year-on-year last year and schools can be, and are, more selective than they have been in the past.
Your decision to go in-person for an interview is an excellent one. It will work in your favor, especially if you’ve come from out of town. I cannot stress enough on the importance of this to candidates applying to business schools. Ask for a campus tour on the day of your interview, if this is offered. And, as others have mentioned, research the school in-depth before going there. If possible, email current students or alumni in advance of your interview with specific and relevant questions about life at school. Most schools will have student representatives or at least contact information listed on their site. Touch upon insight gained through your interactions with current students in your interview, where relevant. As WordMan mentions, they are looking for culture (personality) and fit, and if you haven’t spoken to current students you might not have the insight required to demonstrate your understanding of the culture at school and how you are a fit. All business school websites say pretty much the same thing - “collaborative, team oriented, blah blah”, so just regurgitating what you read on the website won’t give you the insight that you, and they, are looking for. It’s the students that set the culture apart, and know it best.
Oh and one more thing - if, in the interview, you notice your interviewer furiously scribbling on a piece of paper, do not get alarmed. This is normal. They are just taking detailed notes, for future reference and comparison against the candidate pool.
Dress business formal.
Follow up with a thank you note after your interview.