Preheat the oven to 350 degrees. Place the chicken in a covered baking dish, and bake for 25 to 30 minutes. Insert a meat thermometer into the chicken to ensure that it has a safe internal temperature of 165 degrees. Try not to overcook the chicken or it will be a bit dry. Let the chicken cool on a cutting board, then cut it into cubes (yields about 3 cups).
Place the chicken pieces in a large bowl. Add the celery, scallions, raisins, and walnuts to the bowl.
In a separate small bowl, stir together the yogurt (or mayonnaise), lemon juice, curry powder, salt, and turmeric. Pour the dressing over the chicken mixture, and stir to coat evenly.
Transfer the curry chicken salad to an airtight container and refrigerate.