update, to make it vibrate and ring at the same time, and use a mp3 song, you need to instal Buzzme
http://www.bigtincan.com/download_mobile.php, once instaled set the "Call vibration Lengt" to " until stopped", and then go to Profile/option/phone an set the "Out of Holster" to "Tone".
And now, to use a custom mp3, you need to crop a mp3 file to a 300 kbs, or so, if the mp3 is to big, the phone will not play it
PS (sorry for my English)