How to block SPD from editing your sites ?

When I got into the SharePoint world a few years ago, I was told about the damages frontpage can make to Sharepoint websites ( though it can make some good stuff too ).

So one of the first things I did when I start learning about Moss, it's how to block the option of the end user to edit their website with Sharepoint Designer -

1. Go to the onet.xml file ( it's in the sharepoint hive of course ).
2. Look for the line that starts with - "3. Add the - DisableWebDesignFeatures="wdfopensite"
4. Do an iisreset.

Now, You can't edit your sites with SPD.
Good Luck.