Raise your domain functional level

Once all of your DC’s are running Windows Server 2003 or 2008 you can raise the domain functional level by going to active directory domains and trusts.  Right click on active directory domains and trusts then click raise domain functional level.  Once this is done on all of the domains in your forest you can then raise the forest functional level.  Right click  on the forest root except this time select raise forest functional level.