You can add a PDC. Be ready for some overtime. After you get the PDC connected to the network, and you have setup your users and any policies you may or may not want. Are you going to allow for "Home" directories. Anyway, an NT machine is easy. Simply 'add' the NT machine to the new domain. Do this in 'Control panel\networks' and "change" from workgroup to domain. (Must have administrative rights). 95/98 machines aren't much more difficult. Remember to open up "Client for Microsoft Networks" and specify the domain name. Otherwise you'll never see the 3 tiered logon screen. 'username, password, domain'. Also, within the "Identification" tab of 'Control Panel\Networks', be sure that "Workgroup" has the name of your domain. Your set. Have fun.