Also depends very much on the interviewer. Generally, the first impression is the most important one, that''s a human psychological reflex.

The dress code in our company is very relaxed on positions that do not require customer interaction (jeans, t-shirt, pretty much anything you like). It is much more strict, if you have active contact with customers. Personally, I find it very important that people show up appropriately dressed for an interview: suit + tie, no jeans. I do the same, when I interview someone. Even if they end up in a position where it doesn''t matter later on, it''s a sign of mutual respect to show up in decent clothes for an interview, which is basically your first contact with the company.