HERE IS THE SOLUTION:
I found out this solution after a lot of research, and its funny that solution is very simple!
Well, I understand you have upgraded your OS to Windows 8, and your OS does not detect Bluetooth.
Whenever you try to install the Bluetooth Drivers provided by Dell Website, it gives you Compatibility error.
So the solution is this,
Download the Bluetooth Drivers (Dell Wireless 365) from Dell Website (dell.com/support/drivers/) for Windows 7
Install (Extract) the .exe file you have downloaded. In my case it is R228749.exe
Now you get an error message saying "This program is not compatible with this version of Windows.
Don't mind that, instead go to C:/Dell/Drivers. Open the folder where you extracted the files, in my case 83V6K
Now open Win32 or Win64 folder depending on the architecture of your processor. If you're not sure, try the next steps with Win64 first, if you get error try Win32.
Now, in that folder, there is an exe file called Inst. Double click on that and INSTALL.
You now have Windows 8 with working Bluetooth Module on your Dell Inspiron or Vostro or Studio or whatever Laptop ;-)
Hope this helped 🙂 More trouble I or someone else will be happy to help you with 😛
Hashid Hameed