Cook the rice according to the package directions.
Melt the butter in a large saucepan over medium-high heat. Add the garlic and cook for 1 minute. Add the wine, tomatoes, 1/4 teaspoon salt, and 1/4 teaspoon pepper. Simmer for 3 minutes, until the sauce has thickened slightly.
Stir in the shrimp and simmer until cooked through, about 4 minutes.
Add the spinach and stir until wilted.
Spoon the rice into a serving dish or divide among individual plates. Top with the scampi and sprinkle with the tarragon.