To clear confusions Windows 2000 System means
"Where Windows 2000/NT Servers are sole authority for authentication & authorizatoin for users, resources & computers on a Network or a sub network." It does not inculde client side systems plz note that buddy.

And more terminal servers are needed: because other computers that access a terminal server use the resources of that server including CPU, memory...everything. The client acts as a dumb terminal only with a kb & monitor. So starting few graphics demanding application on a terminal server will make it bow down on knees and scum. So even a 1Ghz with 5 users connect on Win2000 Terminal server will make it 200MHz for each user...it is wher linux & unix shine out distinctively. So more manchines are needed to distribute the load.

Active Directory is like a big mess up !! You have to set up group policies & all that stuff is a bloody hell and maintaining is worse.