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