Heat griddle or large skillet to 375°F. In large bowl, combine chicken, cheese and 1 cup of the salsa. Spread margarine on 1 side of each tortilla.
Place 1 tortilla, margarine side down, on hot griddle. Top with 3/4 cup chicken mixture. Place second tortilla, margarine side up, on chicken mixture. Cook until bottom is lightly browned. Turn quesadilla over; cook on second side until quesadilla is lightly browned and chicken mixture is thoroughly heated. Repeat with remaining tortillas and chicken mixture.
To serve, cut each quesadilla into 4 wedges; top with remaining 1 cup salsa and sour cream.