Make the pesto: Drop the pine nuts and garlic through the food chute of a food processor with the motor running; process until minced, stopping to scrape the sides of the bowl as necessary. Add the basil, cheese and lemon juice; process until finely minced. With the processor on, slowly pour the oil through the chute and process until well blended.
Meanwhile, bring a large pot of water to a boil, add a pinch of salt. Cook pasta according to package directions. Drain, reserving 1/2 cup of the pasta water.
In a large bowl, combine 1/2 cup of the pesto (save the rest for another use) and pasta; toss well using the reserved pasta water to thin as necessary. Add the tomatoes, basil and feta. Toss gently to coat. Adjust seasonings with salt and freshly ground pepper.
Per Serving: 492 Calories (30.5% from fat); 17g Fat (4g Sat; 9g Mono, 2g Poly); 15g Protein; 70g Carbohydrate; 4g Dietary Fiber; 10mg Cholesterol; 433mg Sodium. Food Exchanges: 4 1/2 Grain (Starch); 1/2 Lean Meat; 1 Vegetable; 2 1/2 Fat.