Creamy Grape Salad

1 package (8 ounces) cream cheese, softened
1 cup (8 ounces) sour cream
1/3 cup sugar
2 teaspoons vanilla extract
2 pounds seedless green grapes
2 pounds seedless red grapes
3 tablespoons brown sugar
3 tablespoons chopped pecans

In a large mixing bowl, beat the cream cheese, sour cream, sugar, and vanilla until blended. Add grapes and toss to coat. Transfer to a serving bowl. Cover and refrigerate until serving. Sprinkle with brown sugar and pecans just before serving. Yield: 21-24 servings