the $39.99 per adult is the regular
Disney Dining Plan (called "Plus Dining" on their website) Basically, you get 1 table service credit, 1 counter (or "quick") service credit and 1 snack per day. Most Disney restaurants with waiters/menus are 1 table service per person...also buffets are 1 table service per person. There are some exceptions: dinner show like Hoop Dee Doo Revue, the Spirit of Aloha Luau, and such take 2 table service credits per person. Also the "signature restaurants" like the California Grille, Narcoosee's, Cinderella's Royal Table (eating in the castle) and a few others are all 2 table service per person.
For your meal, you are allowed to choose any entree and any dessert off the regular menu, as well as coffee, tea or soda. some places even let you order a non-alcoholic smoothie or milkshake as your
DDP beverage. Most restaurants serve bread or rolls with the meal and every entree we've ever ordered at 20 some different restaurants has come with 2 sides, like mashed potatoes & green beans, or a small fancy salad & rice pilaf...that sort of thing. If there's a filet on the menu, you can order it, even if the price is $35 for that piece of steak.
Here's a link to a pdf version of this year's regular dining plan (usually referred to on these boards as "DDP" for Disney Dining Plan. If you see QSDP, that's the Quick Service Dining Plan, and DxDDP is the Deluxe Disney Dining Plan.)
http://adisneyworld.disney.go.com/m...especific/eng/nontheme/tickets/2009Dining.pdf
This link is to the thread that covers everything & anything about the dining plans:
http://disboards.com/showthread.php?t=2054845
Hope that helps! Have fun on your trip (and make sure you get dinner reservations at 90 days from your arrival date to get into the restaurants you want!)