Place walnuts in a small, heavy bottomed skillet. Toast nuts over medium-heat until lightly browned,shaking skillet fequently, about 1 to 2 minutes; remove from skillet and set aside.

Bring 3 quarts of water and 1/2 teaspoon of salt to a boil in a large pot. Stir in pasta and cook until tender, remove 1 T. pasta cooking water and save for dressing. Drain pasta and place in large serving bowl. Immediatly add arugula and toss well. Cover bowl with a lid tight fitting plastic wrap. Set aside until argula about 5 minutes. Stir in chives and tomatoes.

In a cup, stir together vinegar, oil, reserved tabelspoon of pasta cooking water, remaining 1/4 tsp. salt and pepper in a cup. Poor dressing over pasta and toss well; Sprinkle with blue cheese.