Using a small pan, bring a cup of water to boiling and drop in the mushrooms. Cook uncovered over med-high heat for 10 mins., then drain the mushrooms, pat them dry, and slice thinly. Set aside. In a large saute pan, melt the margarine over low heat. Put in the leeks, carrots, onions, celery and chicken and stir gently. Cover and cook over low heat for 5 mins. Take cover off, stir the vegetables and turn the chicken and check for doneness. (The chicken should be half done.) Cover and cook another 5 mins. or until chicken is just done. Remove the chicken from the pan and set aside to cool. Sprinkle the flour over the melted margarine , vegetables and juices. Stir to cook over low heat for 2 mins. Slowly add the white wine and 2 cups of broth. Stir and cook until bubbly and thickened. Add the sour cream very slowly, and allow to cok gently while you slice the chicken into thin bite-sized pieces. In a large frying pan, bring the remaining 2 cups of broth to boiling and add noodles. Cook 4 mins. or until almost done. Do not drain. Slowly add the noodle mixture to the hot vegetables and sour cream mixture. Add the chicken and the mushroom and bring back to boiling. Serve immediately.