He played college football for the Washington Huskies and was selected by the Indianapolis Colts in the second round of the 2002 NFL draft.

Tripplett attended Westchester High School in Los Angeles, California.

He started all 11 regular season games for the Huskies in 2000, recording 38 tackles, 6.5 sacks, one forced fumble, one fumble recovery, three pass breakups, two blocked field goals and one blocked extra point, earning Associated Press third-team All-American, The Sporting News second-team All-American, espnmag.com first-team All-American and first-team All-Pac-10 honors.

He played in 15 games, starting four, for the Colts in 2005, recording 29 solo tackles, seven assisted tackles, a career-high four sacks, one forced fumble, two fumble recoveries (one of which was returned for a touchdown) and two pass breakups.

He started all 16 games for the second straight season in 2007, accumulating 18 solo tackles, 17 assisted tackles, one sack, one forced fumble, one fumble recovery and five pass breakups Tripplett was released by the Bills on February 29, 2008.