My experience with this is that you can join a Windows
NT machine to a win2k domain without the directory
services snap in and it will function on the network.
Not with Win2003 though and you lose some efficiency even with
Win2000.
However if you rely on group policy etc. on your network
you have to have the client installed to be able to have
the funcionality that windows 2k can offer.
And the above is just not true -- you don't get "Group Policy" functionality
from the DSClient (aka Active Directory Client Upgrade) and such statements
actually indicate that the poster might not have even tried the update since
it
is misnamed.
AD Client Upgrade or DSClient are misleading -- it only makes the clients
site aware, multiple DC-master aware, and provides the ability to do secured
SMB which is important for Win2003.
No REAL support for Active Directory and especially group policy is provided
by these upgrades to pre-Win2000 boxes.