Cut the tops off the peppers, and remove the seeds and set aside.
In a large skillet, saute beef and onions for 10 minutes, or until beef is browned & onions are soft. Drain off excess fat, and season with salt, pepper & garlic powder (to your liking). Stir in the chopped tomatoes & juice, uncooked rice, 2 cups water and Worcestershire sauce. Cover, and simmer for 20 minutes, or until rice is tender. Remove from heat, and stir in the cheese.
Preheat the oven to 350 degrees F. Stuff each pepper with the beef and rice mixture, and place peppers open side up in a baking dish. In a medium bowl, combine tomato soup with just enough water to make the soup a gravy consistency. Pour over the peppers.
Bake covered for 45 minutes to an hour, until green peppers are cooked to your liking.