With support for Windows NT Server 4.0 quickly coming to an end, Microsoft is expecting many of the organizations using NT to upgrade to Windows Server 2003.
Whether Microsoft supports a desired upgrade path depends on the version of operating system your organization is currently running in addition to its service pack level.
The list below displays the editions of Windows Server 2003 that you can upgrade to depending on your organization's current operating system.
Once you've migrated to Windows Server 2003, there are also specific upgrade paths you may take in certain circumstances. If you're running Windows Server 2003 Standard, you may be able to upgrade to the Enterprise or Small Business editions.
However, for organizations running Windows Server 2003 Enterprise, Windows Server 2003 Datacenter, Windows Server 2003 Web, or Windows Small Business Server 2003, there is no edition change allowed.