PREHEAT oven to 325°F. Mix marmalade, peaches, mustard and sherry; set aside.
REMOVE wrapping from ham. Place ham in shallow baking pan. Add water to pan; cover tightly with foil.
BAKE 1-1/2 hours. Remove foil; spoon 1/2 cup of the marmalade mixture over entire surface of ham. Bake an additional 30 minutes or until heated through. Meanwhile, heat the remaining marmalade mixture. Serve with the sliced ham.