Paul Attner wrote an article for the Sporting News today that gets into the details and the path that eventually led the Houston Texans to draft Mario Williams instead of the fan favorite Reggie Bush. Quite an interesting read.
FWIW, and I have stated this already several times, I think in 10 years, the decision will still be a tossup. Both of these guys, Williams and Bush, will be superstars for the foreseeable future.