What that person told you is correct - your X5 is prewired for an old Motorola/Nokia phone that would probably be of no use to you. There is no way to turn it's adaptor into a bluetooth one easily. If you are interested in bluetooth, the most economical and rational route would be to install a Dice Mediabridge (
http://www.xoutpost.com/bmw-related-...-shipping.html). It will require you to sacrafice your 6-CD changer (if you have one), but will give you full bluetooth capabilities with your phone (including streaming music) for about $300.
-Cyrus