If you installed Vista, you’re required to use Mobile Device Center and it seems that the COM settings are missing there. Some mobile devices cannot work without it (like my Motorola Q). However, after many hours I found out that you can solve it by editing your PC registry:
Run regedit.exe > HKEY_LOCAL_MACHINE > Software > Microsoft > Windows CE Services > Modify ‘SerialPort’ entry and change ‘Bluetooth’ to ‘COMx’, reboot and now your mobile device should work with Mobile Device Center via Bluetooth. By the way, if you need some good Bluetooth stack - grab
BlueSolEil VOIP for Vista.