-Server B will still remain NT4 because of SQL 6.5
-We would like to retain Server A because it is also our antivirus server. This cannot be upgraded because it does not comply with the hardware requirements of Windows 2000.
- Domain user accounts, SIDs and the SQL accounts will not be compromised.
What we will try to do is to first install Windows NT 4.0 to server C and make it a BDC. And then we will promote server C to PDC before upgrading it to Windows 2000. I'm just worried about my BDC (server C because of the SQL applications that also use shared folders.)
In addition, the reliance on the single machine holding the AD will put the computing environment and the company at risk. If possible, purchase a second domain controller for the environment. Also, rebuild the 2 NT 4.0 servers so that they are member servers as opposed to domain controllers. If this is all too much trouble, make sure you have a reliable backup of your Windows 2000 Domain Controller. I would suggest testing a full AD restore prior to putting the system in production. Also, use the Windows 2000 Backup to do a regular scheduled SYSTEM STATE backup to a file on the local disk. This will help protect you against failures.