 He came to the United States to attend Butler University in Indiana and finished as the school's third all-time leading scorer with 43 goals and 16 assists.During his college career Armstrong also played for the Mid-Michigan Bucks in the Premier Development League.Armstrong was selected in the second round – 13th overall – of the 2000 MLS SuperDraft by D.C. United but he decided to begin his professional career in Sweden with Västra Frölunda instead before moving to English First Division side Watford on a free transfer in October 2000.