Spincore,

You'll need to install the Vista 64-bit drivers in the Vista SP2 Compatibility mode

Try this procedure and see if the printer installs.

First run Delete Print Jobs to remove any stuck print job in the queue.

Disconnect the printer.

Hit the Windows key and the x keys at the same time, programs and features, your printer, uninstall.

Restart your computer. Make sure the printer is removed. Manual Printer Driver Removal

Download the Vista 32-bit drivers for Windows 7, 8, 8.1 and 10 32-bit or the Vista 64-bit drivers for Windows 7, 8, 8.1 and 10 64-bit. Install the Vista drivers in the Vista Compatibility mode you’ll get a message, the printer is not connected. Connect the printer at this time (powered on).

Links to the drivers can be found at…

Dell 966 Photo All-In-One Printer owners thread (W7)

Remember virus programs and firewalls will block communications.

Rick