The orange hair wouldn't matter as much as the nature of the hair. Is it neatly brushed and clean? Are you dressed in the appropriate interview attire? What I want to see is a level of respect for (future) co-workers and managers reflected in the candidate's appearance; I want to know that they take the interview, and the responsibility to be a "team player", seriously.

If it is important to keep the orange hair, you might want to turn up the "conservative" on the rest of the outfit; go one level dressier in the clothes, and don businessy earrings and maybe a dab of conservatively applied makeup.