Go for the low carb milk, and avoid the sugar content. Even skimmed or powdered milk has a lot of sugar. When you are drinking sugar, it is running through you at such a rate, you cannot hope to burn it as quickly as it is digested.
The low carb milk that I use is chocolate flavor, and has only 2 net carbs (sugar) per 8oz glass, and has 12 grams of protein, as opposed to regular milk which has 12 grams of sugar carbs, and only 8 grams of protein. For some reason the low carb chocolate milk has less sugar than the low carb white variety.
Drinking a lot of milk with a high sugar content is one mistake a lot of new bodybuilders make, because they focus on the protein content exclusively. Protein without sugar is what you really want.