Here's another interview question that many potential job candidates don't give enough attention.  Why do you want to work for OUR firm? Don't you dare say, "Well, I need a job and you're only one of two positions available, so you win."  That would not be flattery.  Don't in any way suggest that you're only interviewing with a company simply because they're your only option and you're desperate.  Also, never suggest that they are your second choice. What you want to do is really think about why you are choosing to interview with this firm.

Go back to your original research notes and ask yourself the following questions:

What is it about this firm's culture that I like?

Example:  I enjoy the fast-paced environment your firm offers.

What makes this firm compatible with my personality, work ethic, personal career goals and passions?

Example:  I'm impressed by your firm's history of allowing junior attorneys get more involved in high-profile cases and see it as an opportunity to learn more...

Are there any recent news items about the firm that impressed you? Maybe the firm has a history of donating to charity or some other noble cause.

Do you admire the people that work there, the partners, CEOs etc?

Think about what it is that would make this firm your first choice.  Right down your answer and be ready to deliver it when this question is asked by the potential employer.