In a large pot, cook pasta according to package directions.
Heat oil in a large pot over medium heat. Add onion and cook for about 4 minutes. Add garlic and cook for about 1 minute more. Add sausage, cook until browned, about 5 minutes. Drain drippings from pot.
Add marinara sauce, basil and oregano and bring to a boil. Turn heat down once it begins to boil, keeping on low until pasta is done cooking.
Once pasta is done, drain water, and add to pot with sauce in it. Stir in arugula, until it begins to wilt. Top with cheese and enjoy!