Win2k Internetworking

I am currently developing a Windows 2000 upgrade plan. I am being told that unless I place a Win2k DC in each remote location from the onset my bandwidth will be consumed by remote clients performing requests for services over the wan. Is this true?Would you point me in the direction of any documentation pertaining to this information. I was planing on upgrading one site at a time and not using the Active Directory Client in any site until a Win 2k DC is in place on that subnet.