The Nashville Predators claimed him in the 1998 NHL Expansion Draft and then in 1999 he was signed as a free agent by the San Jose Sharks.

[1] After spells in the IHL, and AHL, he finally made the jump to the NHL for three games in the 2000–01 season with the Wild.

[2] Armstrong did not play his next NHL game until after he was signed as a free agent by the Mighty Ducks of Anaheim in 2003.

[4] Returning to North America for the 2009–10 season, Armstrong signed as a free agent with the Springfield Falcons of the AHL on December 5, 2009.

[5] In 2003, Armstrong graduated from the Desautels Faculty of Management at McGill University, where he studied commerce.