I have seena few posts that from people that are having troubles with A2DP Support on Vista and Windows 7. i found this post after a google round and it seemed to work for me with no problems

http://windows7forums.com/windows-7-hardware/8235-how-add-a2dp-support-windows-7-a.html

the link for the file is down in the post a bit (or use the links supplied here). This worked for me on an HP nc8430 notebook and the ever3 (everE) headset. all i did was run the setup.exe from the download and it upgraded the BT Stack and rebooted and then i re-paired the head seta and all good

Windows Vista/7 (32/64bit) (Broadcom Generic) - v6.2.0.9700 - 01.09.2009

Windows XP & XP x64 (Broadcom Generic) - v5.5.0.7800 - 17.10.2009 ** NEW **