I thought most Armenians were Catholic or Russian Othodox...
Slight difference in spelling. Arminians are followers of a theological system set forth by Jacobus Arminius (James Arminius) and codified by the Remonstrants of Holland. Armenia is a region in Eastern Europe in the area around Russia, if I remember correctly. Russian Orthodox are more closely aligned with the Eastern (Greek) Orthodox Church, and not so closely with Rome. Arminian churches in America are usually of the evangelical persuasion, althougn you will also find many Baptist Churches among them. Methodists are another Arminian denomination, followers of John Wesley. Calvinists are usually found in the Reformed Churches, some Historic Baptists, and some Independent Churches. I know I'm leaving out a lot, but I'm just answering off the top of my head.
I hope that helps!