Preheat oven to 350 degrees, then grease and flour 2 loaf pans.
Beat sugar and margarine with electric mixer at medium speed until fluffy (about 2 min)
Add vanilla and eggs. Mix well.
Add sour cream, mix well, add flour baking soda and salt, mix well.
Stir in cranberries, divide batter between prepared pans.
Bake bread about 55 minutes until toothpick inserted in center comes out clean.