Line a cookie sheet or large baking pan with tin foil.
Preheat the oven to 375°, putting margarine in the pan and the pan in the oven as the oven preheats so that the margarine will melt.
Remove pan from oven and add pretzels, rice puffs and corn and rice cereal, slowly stirring to coat with melted margarine or butter.
Once all the cereal/pretzels are in the pan, place pan uncovered in oven and bake for 20 minutes.
Once the snack mix is finished baking, remove from oven and allow to cool.
While cooling, in a small sauce pan, over low heat, melt milk chocolate chips with one cup of milk, adding milk slowly until melted.
Repeat for white chocolate chips.
With a spoon, drizzle melted milk and white chocolate over the snack mix and allow to firm.
Once chocolate is more firm, toss and serve.