[chachee52]

Being someone that is doing the interview process right now too, I'd say wearing a tie is always a good idea even if it's not what the "uniform" would be. I'd do the nice pants, button down shirt and a tie. I'm not a dressy type by any means but I make sure that I "clean up nicely" for important situations and a job interview is one of those.
Good luck and I agree with everyone else, be yourself!! I always hated the people that would come in to interview and act one way and then come to work acting and saying the complete opposite. I want them to hire me for who I am and what I do, not for the answers that they want to hear. But then again, I don't like to act, so I am who I am.