Warren Buffett and Bill Gates have both founded highly profitable companies, so it's safe to say that they've made quite a few smart business decisions. In a 1998 panel discussion with students at the University of Washington's business school, the two billionaires pinpointed the best business decisions they ever made. Buffett said his best business decision was simply starting a career in investing because he enjoys what he does. Luckily, said Buffett, this has worked out well for him. "You'll see plenty of times when you get chances to do things that just shout at you," he said. "When that happens, you have to take a big swing." Alluding to his own experiences as an investor, Buffett said that when these opportunities arise, you must act quickly. There's no time to be "reading a book on the theory of diversification," he said. "When you find something where you know the business, it's within your circle of competence, you u...