A lot of the users here are running 98... some 95, and a bunch running Win2k Professional.

The client operating system is not the question, this counts no matter which version of Windows the clients are running.

Here's what counts, and how you answer the question:

When your users log into their computers, do they have two boxes to fill in information(username/password) or do they have three (username/password/domain). If three, then that's the whole trick, that third box.

"Domain" means the domain controller. You're replacing that domain controller and you have to migrate its security database over to the new box and promote the new box to a PDC.