THE O.C. star Kelly Rowan is engaged to the richest man in Canada and plans to marry him before the end of 2007. The 41-year-old beauty, who played Kirsten 'Kiki' Cohen on the now-defunct TV show, will wed media mogul David Thomson, 50, later this year (07). The couple met in Toronto, Canada last year (06), reports website Billionaire Thomson is the 10th richest man in the world, according to Forbes magazine.