Ideally you want something fast absorbing for post workout recovery, and that generaly means a good 100% whey protein powder and anywhere from 60-100g of simple carbs for glycogen replacement. Its up to you just how much simple carbs to use. You need to experiment to see where your tolerance is. I found mine at zero, so it really is a personal matter.
Muscle Milk is not 100% whey, so while its not "bad" for post workout, its also not "optimal". Use Muscle Milk if you want during the rest of the day as a meal replacement shake and dont worry about the fats because they are good fats that you need. Well, to a point. Check your diet to see how much fat you are allowed on a daily basis and plan accordingly.
When making your PWO shake, use only as much protein powder as you're allowed in that feeding. Once again, check your diet to see how many grams of protein you need per meal to satisfy your daily requirements. Just do a general check, you dont have to be on the money unless you are a pro with 3% bodyfat. So dont worry if you go over or under just a bit. If you're just a regular joe/gym rat, such minute percentage management wont make any difference.