A strange sound erupted an hour before the Arizona Cardinals' first game in their new stadium Saturday afternoon. The visiting team was booed as it took the field for pregame warm-ups. This rarely occurred in the Cardinals' former home, Sun Devil Stadium in Tempe, where visiting fans often outnumbered Cardinal faithful. No longer. Cardinals Stadium is sold out for the 2006 season, and the $455 million retractable-domed palace was awash in red as a crowd of 63,400 watched the Cardinals beat the defending Super Bowl champion Pittsburgh Steelers 21-13 in their preseason opener.