A. Upgrading from the standard to the enterprise edition of Windows 2003 opens up a lot of new features and access to additional hardware capabilities, such as more memory. You can upgrade from a standard installation to an enterprise edition in place, but you must upgrade to the same or higher version, which is the problem in this instance.

Server 2003 R2 is Server 2003 with SP1 slipstreamed into it. If you're trying to upgrade from Windows 2003 SP2 to a vanilla Windows 2003 R2 installation (which is only SP1), you're effectively downgrading, which Windows won't allow.

The solution is to either uninstall SP2 from the Server 2003 standard installation or create a new Server 2003 R2 Enterprise disc that has SP2 slipstreamed into it.

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