To Make Crust: In a small bowl, mix together crushed graham crackers and melted butter or margarine. Press mixture into bottom and sides of a 9 inch pie pan.
To Make Filling: In a medium mixing bowl whip cream cheese until fluffy. Beat in 3/4 cup sugar, then add eggs, 2 teaspoons vanilla extract, and lemon juice.
Mix until smooth.
Pour into crust.
Bake in preheated oven for 15 to 20 minutes, until set around edges.
Remove and cool 5 minutes.
Mix together sour cream, 3 1/2 tablespoons sugar, and 1 teaspoon vanilla.
Spread over top of pie and return to oven for 10 minutes. Chill at least 5 hours before serving.