The solution proved the same as before:
- Locate a Windows 7 x64 driver for that card
- Extract the installer to find the driver files
- Go into Device Manager and click Update Driver
- Choose Let me pick the driver to install
- Point to the driver folder
- Hide any updates pushed by Windows Update.
So, for a Dell Latitude 6510, download the following Broadcom driver from the Dell support site (Windows 7 x64):
Navigate to the Drivers\Win7\WL folder and put that location on your clipboard:
Open the Device Manager en locate the Broadcom Wireless-N network adapter. Right click it and choose Update Driver:
And finally navigate to the location you extracted the driver files (which you placed on the clipboard if you followed the instructions to the letter):
Windows will now show you the driver to install. It should automatically highlight the correct option:
It might be that Windows 8 will at some point overwrite the driver with a newer Windows 8 driver version. This is usually an optional update. You can use the "Hide Update" option in Windows Update to fix that :).