When I upgraded from Vista to Windows 7, I discovered that my bluetooth headphones (Backbeat 903) no longer worked on my Sony Vaio computer. It turns out that Windows 7 doesn’t support something called A2DP, which is required for stereo headphones to work. After some research and work, I discovered that the solution is to download and install a new Bluetooth Stack from Broadcom. I uninstalled my Bluetooth headset from Windows 7, then installed the new drivers. Then, I rebooted and set the headset to be rediscovered by Windows 7. I then opened the Audio panel, and set the headset as the default audio. It now works well.