Cut squid bodies into 1⁄2" "rings." If the tentacles are large, cut them in half vertically. Set aside.
Heat olive oil and butter together in a large saute pan. Add garlic and cook over medium-high heat for about 5 minutes. Add tomato sauce, 1⁄4 cup water, and white wine. Cook sauce over high heat for 5 minutes, until it reduces and thickens.
Add all but 1 tbsp. of the parsley to the tomato sauce, lower heat, and simmer, uncovered, for about 15 minutes.
Meanwhile, bring a large pot of salted water to a boil, then add linguini or spaghetti and cook until tender (time will vary according to freshness of pasta, but it should take at least 7 minutes). Drain well, shaking colander gently to remove excess moisture.
Add calamari to tomato sauce, then remove pan from heat and allow to stand, covered, for 2 minutes. Add salt and pepper to taste. Add the drained pasta and toss well. To serve, garnish with remaining parsley.