Cook pasta according to package directions, omitting salt and fat. Drain, and keep warm.
While pasta cooks, coat a large nonstick skillet with cooking spray; place over medium-high heat until hot. Remove casings from sausage. Add sausage and onion to skillet; cook until sausage is browned and onion is tender, stirring until sausage crumbles. Drain and pat dry with paper towels. Wipe drippings from skillet with a paper towel.
Return sausage mixture to skillet; add pasta sauce and red pepper. Bring to a boil; reduce heat, and simmer 10 minutes.
Combine pasta and sausage mixture in a large bowl, tossing well. Sprinkle with Parmesan cheese. Serve immediately.
Use kitchen scissors or a sharp knife to split the casings lengthwise down sausage links. Peel off the casings, then discard them.
Cooking Light Low-Fat, Low-Calorie Quick and Easy Cookbook