They're pretty unambiguous about the policy for '08 being that if you are on the basic dining plan, appetizers are NOT included.
Just from your post, I think you may be talking about the deluxe plan (either that or you are on the regular plan on a visit that begins in '07), which does include appetizers. I doubt they would switch appetizers for desserts (unless you run across a place like CA. Grill that has a cheese plate on their dessert menu) but you can ask if you want to switch an entree for an appetizer, can't believe they wouldn't allow that.