Heat oven to 375°F. In large bowl, combine 1/2 cup sugar, brown sugar and margarine; beat until light and fluffy. Add peanut butter, vanilla and egg; blend well. Add flour, baking soda and salt; mix well. Shape dough into 1-inch balls. Place 2 inches apart on ungreased cookie sheets. With a fork dipped in sugar, flatten balls in cross-cross pattern.

Bake at 375° F. For 6-9 minutes or until set and golden brown. Immediately remove from cookie sheets