Dress is pretty easy for men and there's lots of great advice on this site. Basic advice:
The important thing isn't to be flashy. The point is for your clothing is to not be a point of contention. Great clothes won't really help you, but dressing like an adult will help with your overall impression. Obviously you can depart from this advice and do fine, but this is what I think is the safest route.
Suit: Navy or charcoal. Have normal lapels and nothing too busy. Doesn't have to be a super nice suit--just make sure it's well-tailored so it doesn't look like you have your dad's suit on. No pocket square.
Shirt: White or blue. Normal point collar.
Tie: Not skinny. I prefer silk. Red or blue (including maroon or navy) with a "soft pattern" if you choose to have a pattern at all. Google "the tie bar"--they are cheap and look great. I like http://www.thetiebar.com/order_page.asp?pn=17040
IMO tie bars look bad.
Pants: If pleats, cuff them. If no pleats, up to you (I prefer no pleats).
Shoes: You don't need allen edmonds park avenues, but a black cap-toed oxford that's not too shiny works just fine.
Belt: Try to match your shoes as much as possible. If you have shiny shoes, have a shiny belt. Don't buy brown belts off memory--it's hard to make them match.
Socks: Dark navy or charcoal depending on the color of your suit. Black is fine, too.
There were people dressed in some pretty ridiculous stuff who got offers at wonderful firms, but I know it's hard to keep from over-preparing. Don't feel like you have to go out and buy clothes to match this advice, but I hope it helps you feel confident about what you're wearing heading into the interview.