Bring a large pot of lightly salted water to a boil. Cook pasta for 8 to 10 minutes, or until al dente; drain.
Place whole sausages and 1/3 cup water in a skillet over medium-high heat. Cover, and cook 5 to 8 minutes. Drain and thinly slice.
Return sausage to skillet. Stir in garlic, onions, peppers, and Marsala wine. Cook over medium-high heat, stirring frequently, until sausage is cooked through. Stir in diced tomatoes, black pepper, and oregano. Cook about 2 minutes more, then remove from heat. Serve over cooked pasta.