Skim milk is treated like elixir by the health conscious. It seems the the flawless beverage, allowing you to get all the vitamins found from milk out fat. However, as it turns out, more and more researchers are coming to the conclusion that skim milk is not nearly as good for you as it's full fat counterpart.
The reason behind this is that when the fat is removed from milk, many important vitamins are removed with it, and thus need to be replaced with synthetics. Many manufacturers also "fortify" they skim milk, using a powdered version of milk that can actually serve to oxidize the cholesterol contained in milk.
While this has not be tested in humans, animals that drank oxidized cholesterol were more likely to develop heart disease. So while it may cost you a couple pounds, you may be much better drinking full fat milk.