Drop toasted pine nuts and garlic cloves through food chute with food processor on, and process until minced. Add arugula, Parmesan cheese, water, lemon juice, and salt to food processor, and process until finely minced. With food processor on, slowly pour olive oil through food chute, and process until well-blended. Combine pesto with pasta in a large bowl, and toss well.
Note: Pesto can be prepared ahead of time and stored in a zip-top plastic bag in refrigerator for up to a week.