Most Americans are led to believe through TV and marketing that cows milk is healthy and necessary, but it is not necessary at all. You can get all the calcium you/your child needs through MANY other regular dietary foods. Just because it has a lot of calcium doesn't mean it's the only place get it from. In addition, milk has a lot of stuff people don't need. Cow's milk is designed (made for and made by..) baby cows. Even though humans CAN drink it doesn't mean it's 'doing a body good'!
More are more legitimate research results are available about children and adults consuming cows milk. Studies have been done by many research faclities, colleges and universities. Check out some info on the web and in books and make your own educated decision about whether or not you want to continue giving it to your child, or if so, how often. Kids already generally get lots of diary in yogurt, cheeses,ice-creams).
I believe Dr.Sears parenting books esp. The Nutrition Book and/or his website, the Mothering.com site and another site called nomilk.com (I think, or it's something close) all talk about children and cow's milk. Organic almond milk is a great alternative if you really want a creamy drink, and you can even make your own! Otherwise, water is the best choice!