Which 'American Idol' winner became a country music superstar after winning Season 4?

Who hosted the original U.S. version of 'Who Wants to Be a Millionaire'? Which contestant holds the record for the longest winning streak on 'Jeopardy!', with 74 wins? Which reality competition show featured Simon Cowell, Paula Abdul, and Randy Jackson as original judges? Who won the first season of 'American Idol' in 2002? Who has hosted 'American Idol' since its first season? Which reality show features contestants voted off an island, with host Jeff Probst? Which reality show features teams racing around the world, hosted by Phil Keoghan? Which reality series followed a family consisting of Kim, Khloé, and Kourtney?