Raise your domain functional levelJuly 13, 2009
Seizing domain controllers FSMO rolesJuly 14, 2009
In 2003/2008 after you upgrade your domain and forest functional level you shold move AD integrated DNS to the application partition. This can be done by going to the DNS manager>Forward lookup zones>right click on the zone that applies to your domain and click properties. Click the chage button. Select either to all dns servers in active directory forest or to all dns servers in active directory domain.