1.Combine The Walnuts, Garlic, Arugula, And Cilantro Or Basil In A Food Processor Or Blender. Whirl Them Just Until They Are Coarsely Chopped. While The Machine Is Running, Add The Olive Oil In A Thin Stream. Transfer The Pesto To A Bowl. (At This Point The Pesto Can Be Frozen. Thaw It Before Proceeding.) 2.Stir The Parmesan Cheese, Salt, And Cayenne Into The Pesto 3.Bring A Large Pot Of Salted Water To A Boil. Add The Pasta, And Cook It, Stirring Occasionally, Until It Is Just Tender. Drain The Pasta, Return It To The Empty Pot, And Toss It With The Pesto, Adding A Tablespoon Or Two Of Water If Necessary To Distribute The Pesto Evenly. 4.Transfer The Pasta To A Serving Bowl Or To Individual Plates, Garnish With Additional Parmesan Cheese And Serve.