Got a Dell XPS Studio 1645 (Win 7 64 bit) and this system has a Dell Wireless 370 Bluetooth (BT) card.
Follow the below steps to stream audio from your Android smartphone (I have Moto G Android 4.4) to Dell system (XPS 1645(Win 7 64 bit)) with Dell Wireless 370 Bluetooth (BT) card.
1. Make sure in your BIOS -> Wireless -> Bluetooth is enabled (This means your system has Bluetooth capability).
2. After booting to Win 7 goto Dell site and download the driver from www.dell.com/.../DriversDetails
3. After Download make sure you are logged in as Admin and make sure your right click and "run as Administrator"
4. The file will unzip and start the installation, if installation doesn't start it means you are not logged in as Admin
5. Restart your system (its a must) after successful installation.
6. After restarting you can see Bluetooth devices Icon in your task bar (near date/time)
7. In your dell PC right click on the Bluetooth icon in task bar and click on "Open settings" and make sure you have "Allow Bluetooth devices to find this computer" enabled and under connection "Alert me when a new Bluetooth device wants to connect".
8. Restart the Dell PC.
9. Now its time to make your Android 4.4 to have capability to stream audio to do this you need to go to Android market (Google play). Search for "Auto Bluetooth Volume A2DP" from Ksoft (its free). Once installed restart your phone. Goto Phone Settings and look for Bluetooth, touch it and down you will see "Scan for devices", you will see your Dell PC name in the list. Touch the Dell PC.
10. Right click on the bluetooth icon in task bar of your Dell PC and you can see "Allow Device to connect" will be enabled now, click on it and on your phone there will be a code displayed, which you can see on the Dell PC now. Click on "Yes" in DELL PC and it will take a while to pair.
11. Once paired, restart your Dell PC.
12. Now look for the app that you installed on the phone (Auto Bluetooth Volume A2DP) you will see the widget as "Bluetooth Volume", touch it and on the upper right corner there will be 3 vertical dots, touch that and a menu will open, touch preferences and enable the "Respond to Car Mode". Restart your phone.
13. If your steps 10/12 are successful on your DELL PC right click on the Bluetooth icon on task bar and click "Show Bluetooth Devices". You can see your phone on the window that has opened.
14. Right click on that phone icon and click on properties, you will be able to see "General", "Hardware", "SErvices" & "Bluetooth". Click on SErvices and after some time it will display all the services that bluetooth connection supports. Make sure you have enabled "Advanced Audio". As you do that Win 7 will start installing further device drivers.
15. After the drivers are installed on DELL PC there will be a window opened "Bluetooth Phone Operations and SEttings" Under Configuration and Settings you will have Authorization Options. Click/Select "Always allow this device to connect for all operations"
16. In the same "Bluetooth Phone Operations and SEttings" Under Phone Operations you will have "Start listening to audio from your phone (XXXXXXX) through this computer's speakers" & "STart using this computer as a headset or speaker-phone for calls on your phone". There will be a connect button, click on the Connect button for "Start listening to audio from your phone (XXXXXXX) through this computer's speakers" and a small player will open on your Dell PC, click on play and songs on your phones default player will start play but the sound will come from your DELL PC.
You can click on the connect button of "STart using this computer as a headset or speakerphone for calls on your phone" and your phone will start dialling the last number you dialled but the ring tone will be from your DELL PC.