I found a way in Windows 7 to play audio and receive phone calls from Windows 7 using Bluetooth. I use rooted Samsung Galaxy ACE running on Android 2.3.
- Pair your phone with PC
- Go to Control PanelAll Control Panel ItemsDevices and Printers in the PC
- Double click and open the Bluetooth Control
- Click connect button for using the computer speaker to during phone calls and play music from PC using mobile phone's audio player
- You will notice a small media player control at the right bottom of the screen where you can play/pause/change songs which is being played in the phone.
Note that I have not found a way to choose to pick up calls from PC, it automatically picks up after few rings. May be I have to play around the settings more. Anyway this helps improving the phone signal strength of my phone because we don't have to attach the phone to our ear.