Grape salad

Got this recipe from my mom ... I think she got it out of a cookbook?

4 lbs seedless grapes. (I personally like the red grapes best)
1 (8 oz) cream cheese softened to room temperature
1/2 cup sour cream
1/2 sugar
1 tsp vanilla

Cream all went ingredients together. Fold in grapes. (Be sure you don't wash the grapes... you can use a damp paper towel to wipe them off if you'd like)

Topping:
1 cup brown sugar
1 cup finely chopped nuts (I think it's pecans. I use either that or walnuts. I can't remember. I think both are pretty good)

Spoon mixture on grape salad and lightly pack. Store in refrigerator overnight before serving - uncovered.