Sprinkle gelatin over water in small saucepan. Let stand for 10 minutes until gelatin softens. Turn on heat to low and stir until gelatin dissolves. Let stand approx 10 minutes until cool but not set.
Place sour cream in bowl. Stir in gelatin mixture.
Place medium bowl in freezer for 15 minutes. Add whipping cream, sugar and vanilla to chilled bowl and beat with electric mixer until soft peaks form; fold into sour cream mixture. Cover; chill at least 1 hour.