Preheat oven to 250 degrees. Mix pretzels, crackers, cereal and nuts together and pour into a large sheet pan. Melt margarine and stir in worcheshire sauce, salt, garlic powder and onion powder. Pour liquid mixture over mix. Roast in oven for 1 hr, stirring every 15 minutes. (Add your favorite crackers, cereal, nuts as desired. I even add M&M's to give that salty and sweet taste!)