DE SHAW INTERVIEW

i saw a posting on my school's career website from DE shaw. Its for its Fin Ops generalist and generalist associate programs. i applied to both. i have read on this site that these positions are almost impossible to get, and are only given to people who are bloody brilliant. im not a grandmaster chess player/phd or a bloody mystery novel author. im just an average guy who works his ass off. needless to say im NERVOUS. now im wondering what the interview is like and especially what kind of brainteasers are these guys gonna ask at the interview...I have a coupla weeks so I really want to prepare. Any insight on this would be fantastic and greatly appreciated.