Armstrong was born in Dunedin, New Zealand and attended Otago Girls" High School there. In Australia she was affiliated with the Middle Harbour Yacht Club in Mosman, New South Wales. Armstrong again competed for Australia at the 2004 Summer Olympics.
She won a gold medal in the 470 Class with Belinda Stowell at the 2000 Summer Olympics in Sydney. On 16 January 2001, Armstrong was awarded the Australian Sports Meda Ten days later on 26 January 2001, she was awarded the Order of Australia Medal for service to sport as a gold medallist at the Sydney 2000 Olympic Games.
