On my old Centro, there was a setting for the phone to only vibrate if not in your contact list. I loved this feature when I was somewhere and the phone would only ring for those people I wanted it to ring for. All others would just vibrate.

How can I recreate this on my pre. Do I have to create a silent ringtone as a default and then assign regular ringtones to my contacts? Or is there an easier way to recreate this?