Rupp played high school hockey at St. Edward High School in Lakewood, Ohio. He was originally drafted in the first round, ninth overall, by the New York Islanders in the 1998 NHL Entry Draft. After remaining unsigned while still playing in the Ontario Hockey League (OHL) with the Erie Otters, however, Rupp opted to return to the NHL Entry Draft and was subsequently selected 76th overall in 2000 by the New Jersey Devils.