The suit gains you 5 seconds of respect until you open your mouth. Then hopefully you will actually know something.
Do yourself a favor; instead of taking an hour the night before to make sure your shirt is pressed and your socks match get on the web, research the company you are interviewing at, try to assess some of the problems that they may encounter, study up on the languages that they utilize, review your algorithms book, and treat the interview like you're applying for the lead position for the development of an auto-pilot software system for a Boeing 787.
If you know your field and know it well superficialities such as a wrinkled shirt will take a back seat.