In case you want to Restrict the use of SharePoint designer in SharePoint 2010

SharePoint Designer 2010 has been significantly improved and we all use it,
however, there are still scenarios where you, as an administrator, will want to disable or restrict the use of SharePoint designer in your farm.
In SharePoint 2010, you are able to disable or restrict some of the features provided by SharePoint Designer on a Web Application basis.

Go to Central Administration -> General Application settings -> Configure SharePoint Designer settings. You can also configure these settings from the Application management in Central administration