I found this option in webmaster tools and I'm not sure whether it's good or not to change it. It can either Don't set a preferred domain Display URLs as www.xxxxxxx.com Display URLs as xxxxxxx.com If you specify your preferred domain as http://www.example.com and we find a link to http://example.com, we'll consider both links the same. Learn more about setting a preferred domain. ---- Is this worth changing? Can it help?