Combine softened cream cheese and margarine, mixing until well blended. Add flour and salt; mix well. Form into ball; chill thoroughly. On lightly floured surface, roll out dough to 12 inch circle. Place in 9-inch pie plate. Trim and flute edge; prick bottom and sides with fork. Bake at 400^ for 15 minutes or until golden brown.
For tart shells, divide dough into 24 balls; press into mini muffin pan. Bake at 400^ , 10-12 minutes.
For pies that bake longer that 40 minutes, cover rims of pie with foil to prevent excess browning.