KMS host key = This key is obtained from the VLSC. This is the key that you would use during the install of the KMS host when setting up a Office 2010 KMS server

KMS Client Key = This is a generic key that is hardcoded into all of the Office 2010 client products. ie.. ProPlus, Visio, Project.
This key allows the product to be installed without manually entering a product key. Also, when this key is installed it triggers the Office product to attempt to locate and activate against a KMS server.

Volume license versions of Office 2010 are hardcoded with a generic KMS Client Key. This key can be located by opening the setup.xml file from the *.ww folder of the product.

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As an example,  here is the built-in KMS Client Key from the Visio 2010 volume license setup.xml
 
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Visio is a unique product in the volume license space in that Visio can install as Visio Standard, Visio Professional, or Visio Premium based upon the key that is input. By default, Visio 2010 uses this Visio Premium 2010 KMS client key, which enables all the features that are available for Visio Premium 2010. If you are licensed to use Visio Standard 2010 or Visio Professional 2010, you must install the appropriate KMS client key. Different features or applications are available, depending on the kind of key that is installed. This makes it easier for you to upgrade or downgrade without having to deploy a different product edition.

If your license agreement with Microsoft is for Visio Standard 2010 or Visio Professional 2010, use the appropriate Generic KMS client key shown in the following table.

Visio edition KMS client key

Visio Standard 2010

767HD-QGMWX-8QTDB-9G3R2-KHFGJ

Visio Professional 2010

7MCW8-VRQVK-G677T-PDJCM-Q8TCP

Visio Premium 2010

D9DWC-HPYVV-JGF4P-BTWQB-WX8BJ

For information about how to plan your Visio Professional 2010 installation, see Plan customizations and options for Visio 2010.

There are two scenarios to consider for installing an appropriate KMS Client key.

Scenario 1

Visio 2010 has already been deployed in your organization.
At the time of the deployment no key was specified and as a result everyone has Visio Premium installed although the organization is licensed for Visio Standard 2010 or Visio Professional 2010.

To downgrade these versions from Premium to Pro or STD, they will need to change the installed KMS Client key to the generic PRO, or STD key using a script that calls ospp.vbs , or by using VAMT. After the key is changed it will automatically activate against the KMS s host server, provided the KMS host is healthy and reachable.

Method 1 – Using a script that calls ospp.vbs on the machine to install a new KMS Client key. This script can be pushed out as a startup script via GPO to the affected machines.

Here is a simple, example batch file script that I have used to install the Visio 2010 Client key for Standard edition post install. This should work on X86 and X64 machines. I have placed a registry key query in this script so that it checks for the existence of a registry key that does not exist natively, and then when the script runs it adds that dummy registry key. This way the next time the script runs (if deployed as a startup script for example) it will simply end when it locates the dummy key that had been added during the script’s previous run.

OSPP.BAT                                                                                                                                                                                                                                                           

@echo off

if "%PROCESSOR_ARCHITECTURE%"=="x86" if "%PROCESSOR_ARCHITEW6432%"=="" goto x86
set ProgramFilesPath=%ProgramFiles(x86)%
goto OSPP

:x86
set ProgramFilesPath=%ProgramFiles%

:OSPP
reg query HKLM\Software\Microsoft\Office\14.0\Common\OSPPRUNONCE
if %errorlevel%==1 (goto RUN) else (goto END)

:RUN
C:\Windows\system32\cscript.exe "%ProgramFilesPath%\Microsoft Office\Office14\ospp.vbs" /inpkey:767HD-QGMWX-8QTDB-9G3R2-KHFGJ
C:\Windows\system32\cscript.exe "%ProgramFilesPath%\Microsoft Office\Office14\ospp.vbs" /act
REG ADD "HKLM\Software\Microsoft\Office\14.0\Common\OSPPRUNONCE"

:END
Exit

Method 2 – Use the VAMT tool to install a different KMS Client key for Visio 2010 post install.

For more information and a walkthrough of the Volume Activation Management tool

Managing Office 2010 Activations using the Volume Activation Management Tool (VAMT 2.0)
http://blogs.technet.com/b/odsupport/archive/2010/08/06/managing-office-2010-activations-using-the-volume-activation-management-tool-vamt-2-0.asp

 

Scenario 2

Visio 2010 has not yet been deployed in the organization and we need to ensure that correct edition of Visio 2010 is deployed.

If the organization is not licensed for Premium, they will either need to ensure that they modify the config.xml (in the visio.ww folder) and include the generic KMS client key for Pro or STD, or create a custom.msp file with the Office customization tool and specify the generic KMS client key for Pro or STD. After the install Visio will activate against KMS without issue if the KMS host is activated, healthy and has had the 5 minimum unique requests.

Method 1

Modify the config.xml to specify the KMS Client key to use.  If we specify the KMS Client key for Standard edition in the config.xml file from the Visio.ww folder, than Visio will install with that KMS Client key instead of the built-in key for Premium.

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As an example, here is a modified config.xml with the generic KMS Client key for Standard specified.

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Method 2

Create a custom MSP file with the Office Customization Tool to specify the KMS Client key to use.  If we specify the KMS Client key for Standard edition in the Office Customization Tool and save the custom MSP in the updates folder, Visio will install with that KMS Client key instead of the built-in key for Premium.

Open the Office Customization Tool by calling setup.exe with the /admin switch

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In the OCT under the Licensing and user interface section, you can choose “Enter another product key” and input your generic Pro or STD KMS Client key.

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After saving the custom MSP file from the Office Customization tool, make sure to place the custom MSP file in the updates folder of the Visio source. Now when your Visio installation takes place it will use the custom msp file you created in the updates folder and apply your generic Pro/STD key rather than the built in Premium key.

This is also discussed in the following technet article:

Deploy volume activation of Office 2010
http://technet.microsoft.com/en-us/library/ee624357.aspx