"pre-stuffed (dressing as I know it) turkey"

Sounds like the bird is already stuffed. It's true that some culinary experts suggest not stuffing poultry. Gnu, was there no cooking information with the bird?

Here's a good basic set of directions for various meat thermometers:

http://www.globalgourmet.com/food/egg/egg1197/meatherm.html#axzz1lRbYNhMo

Cook's Illustrated (my favorite source for cooking questions)
suggests lining the bird's cavity with cheesecloth, roasting the turkey, then removing the stuffing before roasting the turkey to the correct temperature. In part,

"...4. TO ROAST THE TURKEY: Combine remaining 2 teaspoons kosher salt and baking powder in small bowl. Remove turkey from refrigerator and unwrap. Thoroughly dry inside and out with paper towels. Using skewer, poke 15 to 20 holes in fat deposits on top of breast halves and thighs, 4 to 5 holes in each deposit. Sprinkle surface of turkey with salt-baking powder mixture and rub in mixture with hands, coating skin evenly. Tuck wings underneath turkey. Line turkey cavity with cheesecloth, pack with 4 to 5 cups stuffing, tie ends of cheesecloth together. Cover remaining stuffing with plastic wrap and refrigerate. Using twine, loosely tie turkey legs together. Place turkey breast-side down in V-rack set in roasting pan and drape salt pork slices over back.

5. Roast turkey breast-side down until thickest part of breast registers 130 degrees on instant-read thermometer, 2 to 2 1/2 hours. Remove roasting pan from oven (close oven door) and increase oven temperature to 450 degrees. Transfer turkey in V-rack to rimmed baking sheet. Remove and discard salt pork. Using clean potholders or kitchen towels, rotate turkey breast-side up. Cut twine binding legs and remove stuffing bag; empty into reserved stuffing in bowl. Pour drippings from roasting pan into fat separator and reserve for gravy, if making.

6. Once oven has come to temperature, return turkey in V-rack to roasting pan and roast until skin is golden brown and crisp, thickest part of breast registers 160 degrees, and thickest part of thigh registers 175 degrees, about 45 minutes, rotating pan halfway through. Transfer turkey to carving board and let rest, uncovered, 30 minutes.

7. While turkey rests, reduce oven temperature to 400 degrees. Whisk eggs and remaining 1/2 cup broth together in small bowl. Pour egg mixture over stuffing and toss to combine, breaking up any large chunks; spread in buttered 13- by 9-inch baking dish. Bake until stuffing registers 165 degrees and top is golden brown, about 15 minutes. Carve turkey and serve with stuffing."http://www.cooksillustrated.com/recipes/detail.asp?docid=20850