We're guessing even Simon is speechless right about now. Five months after finishing runner up to Ruben Studdard on American Idol by just 1 percent, Clay Aiken has shown himself the biggest Idol of all where it counts--on the charts. Making A.I. sales history, the nerdy North Carolinian's Measure of a Man sold a whopping 613,000 copies last week, according to SoundScan numbers released Wednesday. No other Idol has sold even half that amount in a week. Last April, inaugural champ Kelly Clarkson (news) sold 297,000 of her debut disc, Thankful, to top the charts and Aiken spoiler Studdard sold...