Ritchie scored twice to give him a team-leading 38 goals on the season, and added two assists, while Strome scored once and set up three more.
Trevor Murphy, Nick Ebert, Ryan Verbeek and Alexander Khohklachev replied for the Spitfires (24-31-8).
Rookie Brent Moran picked up the win in net making 34 saves, while former IceDog Jaroslav Pavelka turned aside 29 shots in the loss.
Niagara finished the game 2 for 4 on the power play. Windsor went 2 for 8.