Complex sentence: Vieira was the original host of the United States syndicated version of "Who Wants to Be a Millionaire", for contributing to "Dateline NBC", "Rock Center with Brian Williams", and for presenting Lifetime Television's "Intimate Portrait" series.
Split into simpler sentences: Vieira was the original host of the United States syndicated version of "Who Wants to Be a Millionaire". She has been a contributor to "Dateline NBC" and "Rock Center with Brian Williams", and was the presenter on Lifetime Television's "Intimate Portrait" series.