Remove grapes from stems and wash. Dry them as much as you can, then set aside.
In a large bowl combine cream cheese and sour cream or yogurt. Beat with an electric mixer until smooth. You can do this step by hand if your cream cheese is very soft.
Add sugar or honey to taste. Add grapes and fold in until the dressing evenly coats all of them. Transfer to a serving dish and sprinkle with brown sugar. Chill for at least 2 hours.
When ready to serve, sprinkle with chopped walnuts.
Notes
Toasting the nuts will enhance their flavour. You can dry toast them in a pan on the stove or in the oven at 350F/180C for 7-10 minutes.