Wash, peel and dice all potatoes into 1/2-inch pieces. In large skillet, saute diced bacon until brown, add butter; heat until melted. Stir in potatoes and onion, saute, covered, until potatoes begin to soften (10-15 minutes), stirring occasionally. Stir in seasonings and arugula; stir until arugula begins to wilt. Serve immediately.