Cream cheese frosting recipes that call for 8 oz. cream cheese and a whole stick of margarine usually require at least 1 pound of powdered sugar. Keeping the cream cheese and margarine chilled is a good idea unless you want to take the cake somewhere where it will not be refrigerated for a while. I have had good success with this recipe. I use it on Italian Cream, Carrot Cake, etc.

Cream Cheese Frosting
1 - 8 ounce bar Cream Cheese
2 Tablespoons margerine
1 box powdered sugar (about 4 cups or 1 pound)
1/2 c. flour
1/2 t. salt

Cream cheese and margarine. Add remaining ingredients gradually. Frost cooled cake.