Oh, there is something important to add: on Google.de, Google has sometimes (!!!) problems with
www.mydomain.com vs. mydomain.com; it seems sometimes Google treats the same domain without www as duplicate ;-). It is ridiculous but it is true.
When starting a new project, eg
www.mydomain.com I recommend to put the following code snippet into your .htaccess
RewriteEngine On
RewriteCond %{HTTP_HOST} !^www\.mydomain\.com$
RewriteRule ^(.*)$ http://www.mydomain.com/$1 [L,R=301]
Greets