How to Block SharePoint 2010 Installation ?

If you want to block users from installing SharePoint Server 2010 and related products, set the following registry key by using Group Policy in Active Directory directory services:

HKLM\Software\Policies\Microsoft\Shared Tools\Web Server Extensions\14.0\ SharePoint\DWORD DisableInstall

To block installations, set DWORD DisableInstall=00000001.

When this registry key is set, users who try to install SharePoint Server 2010 receive the 

following error message:

SharePoint installation is blocked in your organization. Please contact your network administrator for more details.

To set a registry value by using Group Policy, you can use an .admx file in Windows Server 2008 or a Windows PowerShell cmdlet in Windows Server 2008 R2.

For more information about how to set registry values by using group policies in Windows Server 2008, see Group Policy ADMX Syntax Reference Guide (http://go.microsoft.com/fwlink/p/?LinkId=194348).

For more information about how to set registry values by using group policies in Windows Server 2008 R2, see Set a registry key value from the command line using Group Policy PowerShell cmdlets (http://go.microsoft.com/fwlink/p/?LinkId=194345).

For general information about group policies, see Group Policy (http://go.microsoft.com/fwlink/p/?LinkID=177635) on TechNet.

MS reference: http://technet.microsoft.com/en-us/library/2296f7de-02a2-4ca6-b5e8-cafc740957a6#Block