1Melt margarine in 3-quart saucepan over medium heat. Cook onion and garlic in margarine, stirring occasionally, until onion is tender.
2Stir in remaining ingredients except cheeses, breaking up tomatoes. Heat to boiling; reduce heat to low. Cover and simmer 15 minutes, stirring occasionally.
3Stir in Cheddar cheese and 1/2 cup of the Monterey Jack cheese. Heat over low heat, stirring occasionally, just until cheeses are melted. Sprinkle each serving with remaining Monterey Jack cheese.