DS1 nursed until 20 months and I introduced cows milk just after 1 year when I returned to work.
I made sure he had no more than 8-12 oz per day because I was worried about him replacing food with milk, iron absorption issues, constipation, etc. He would eat cheese / yogurt also. Even though he was at daycare, they were not to offer him any dairy except for what I sent also.
DS1 is now 3 and he likes cows milk, prefers water though, but I still limit the amount, not necessarily daily but weekly.
Loving my two wild and crazy boys -- DS1 06/07 and DS2 12/09