1. Move all FSMO roles to one domain controller and configure all the DC’s as GC’s.
  2. Move the domain controller from step 1 to unique VLAN that will be isolated from the regular network.
  3. Backup the domain controller from step 1 by using backup tape backup, and some image utility.
  4. After running ADPREP /Forestprep check that Windows 2003 schema upgrade to contain new 2003 forest attributs.
  5.  After running ADPREP /Domainprep check that Windows 2003 schema upgrade to contain new 2003 domain attributs.
  6. Disable any antivirus software on the software before the upgrade process.
  7. Log on to the domain controller from step 1 with account that member of: Enterprise Admin group, Domain Admin group, Schema Admin group – and if you have Exchange System in your organization – the account should be with Full Exchange Admin permission on the Exchange organization, administrative groups (sites in Exchange 5.5 environment), Exchange Servers (and in Exchange 5.5 environment – also full control on “Configuration” container).
  8. Test this upgrade in a lab before implement it on production server.
  9.  Copy the I386 directory content from the Windows 2003 cd rom, to the local server hard disk.
  10.  Verity that the all servers in the domain have the correct time zone and the configure to be synchronization from the same server (usually this the PDC emulator).
  11.  Activate the new Windows 2003 Server before implement any changes on the system.
  12.  If you add new Windows 2003 server to the domain, make sure to configure the correct domain name and domain suffix.
  13. Don’t use forbidden characters in the domain or/and server name (etc *, _).
  14. Before you implement – Windows 2003 CA, Windows 2003 Cluster, Exchange 2003 configure at least one DC as Windows 2003 DC and GC, and configure Windows 2003 CA, Windows 2003 Cluster, Exchange 2003 to use this server as default logon server.
  15. If you have multidomain hierarchy, upgrade first the forest root domain, and only after this upgrade complete, the rest of the forest.
  16. If you have multisites hierarchy, let the changes of ADPREP command to repliacte to all other sites. Verify that each DC upgrade its schema version before you install the Windows 2003 Server.
  17. After running ADPREP command, open %systemroot%\system32\debug\adprep\logs\ADPrep.log, and see if there are error messages that might need to be resolved.
  18. Read: How to Troubleshoot Inter-Forest sIDHistory Migration with ADMTv2 article before beggining the migration. http://support.microsoft.com/default.aspx?scid=kb;en-us;322970
  19. If you installed Exchange 2000/2003, its recommended to run Policytest.exe utility before the upgrade: http://support.microsoft.com/default.aspx?scid=kb;en-us;281537&FR=1&PA=1&SD=HSCH
  20. Read: HOW TO: Upgrade a Windows NT 4.0-Based PDC to a Windows Server 2003-Based Domain Controller http://support.microsoft.com/default.aspx?scid=kb;en-us;326209 HOW TO: Set Up ADMT for a Windows NT 4.0-to-Windows Server 2003 Migration http://support.microsoft.com/default.aspx?scid=kb;en-us;325851 How to Use Active Directory Migration Tool Version 2 to Migrate from Windows 2000 to Windows Server 2003 http://support.microsoft.com/default.aspx?scid=kb;en-us;326480 Active Directory Migration Tool v3.0 http://www.microsoft.com/downloads/details.aspx?FamilyId=6F86937B-533A-466D-A8E8-AFF85AD3D212&displaylang=en How to Upgrade Windows 2000 Domain Controllers to Windows Server 2003 http://support.microsoft.com/default.aspx?scid=kb;en-us;325379 Upgrading to Windows Small Business Server 2003 http://www.microsoft.com/WindowsServer2003/sbs/upgrade/default.mspx Domain Migration Cookbook http://www.microsoft.com/technet/prodtechnol/windows2000serv/deploy/cookbook/cookchp1.mspx Windows Server 2003 PKI Operations Guide http://www.microsoft.com/technet/prodtechnol/windowsserver2003/technologies/security/ws03pkog.mspx
  21. If the upgrade process need to take more then a few hours, consider to change the domain configuration to eliminate Overloading on the First Domain Controller. How to Prevent Overloading on the First Domain Controller During Domain Upgrade http://support.microsoft.com/?kbid=298713