My own thoughts: if the position is technical, then dress business casual, e.g. brand-name plaid shirt and Kakki. If the position is more managerial or sales, then dress formal, e.g. suit and tie. Sports jacket is a good substitute for full suit. In case you don't know what the company's culture is, I would recommend to over-dress just a little bit rather than to under-dress, this way you can be a little bit more confident.
However I don't think how you dress is a deal breaker. Of course you shouldn't be unhygienic (dirty smelly hair, bad breath, dirty fingernails, etc.), but as long as you are clean and appear energetic, apparels are not an issue. After all, interviews are all about perception: what do you want to be perceived as.