Nothing kills an interview faster than an unprepared interviewee.
Know your strengths, skills and capabilities, and how you can contribute to the company's long-range goals. Try to find out what it is that the interviewer will be looking for. Formulate a few key questions about the position to ask your interviewer, and rehearse for your interview by role playing with a friend. Chances are the recruiter has worked with the company before and can provide some insight to the company, the position, the corporate culture, etc. In high tech, many feel that a dapper appearance is not as important as skills and abilities, since most likely your job will involve extensive interfacing with machines who really don't care if you're dressed at all.