rcado's version of Rihanna's "Umbrella" added little, but then she came back strong with Alicia Keys' "If I Ain't Got You" and a rousing performance of the "Dreamgirls" anthem "Listen" that brought the crowd to its feet. But the audience seemed to be saving most of its energy to create jet-level noise for Archuleta and Cook. Archuleta, who was nursing a bad cough Thursday afternoon, did not falter on the Robbie Williams ballad "Angels," OneRepublic's "Apologize" and "Stand By Me." His voice remained strong throughout, and the audience rewarded the teenager with adoring screams. But then something different was at play with Cook. While much of "American Idols Live" felt timed down to the second and engineered down to the microns, Cook seemed relaxed, as if he was playing a club date in front of 100 people. He's not yet doing his own material, but Cook is a skilled interpreter — when he sang Lionel Richie's "Hello" or Billie Jean" by Michael Jackson, he performed to his strengths, bringing stadium rock bravado to the songs. He also proved he could make his "Idol" single, "The Time of My Life" and Aerosmith's "Don't Want to Miss a Thing" fill the room, and did more than mere justice to Foo Fighters' "Hero." Flicking guitar picks to the crowd like he was playing games in the family rec room, Cook simply looked at home. "American Idol" never looks like a relaxed pursuit, but Cook was just his natural self, rocking his face off and clearly enjoying the moment. The "American Idol" machine can seem overpowering in its artifice and calculation, but when Cook was on stage, the machine fell away to reveal an exceptional regular guy who deserves his "Idol" title.