Well I was just curious what the ratio is since my feeling is maybe 10% of people would wear a tie. Since they offered to take me to lunch when I arrive, it would be retarded to be the only person dressed up. Otherwise I was still going to do a tie.

Not once have I worn a suit at an interview (nor do I own a suit) and yet I still managed to get most of the jobs I applied for. I'm far from being a pro in anything, but I do believe your frame of mind matters more when you are doing interviews. For instance, I never get high strung about not getting the job; therefore, I don't get consumed by thoughts of performance, whether I'm wearing the right attire, or become overly self conscious. If you are able to have relaxed Q&A session and able to demonstrate that you are a down-to-earth person (and have the right qualifications), you will be looked upon more favourably. Remember that employers don't just scrutinise your skills, they also asses whether you fit-in their work culture. More importantly, you are also interviewing them. Of course, this not applicable for every job out there, but it's something to think about. For instance, recruiting agencies will most likely look out for candidates that fit the dressy stereotype.

Personally, I'd never wear jeans to a job interview, no matter what. The farthest I'd feel comfortable dressing down is a polo shirt and khakis; anything less than that, and I'd feel like I wasn't taking the interview seriously, no matter what the interviewer him/herself thinks.