external HDD can't be initialized "the device is not ready"

One option would be to boot from a live cd like Partition Wizard or GParted to run the format option while no Windows processes or even some 3rd party app is trying to access the drive. This will also bypass any write protection since no OS is running.

If the drive has any software such the volume being exFat to see it mounted in Vista that may be one reason for the write protection error being seen. Vista lacks any Fat support while 7 saw it returned just for things like external hard drives and flash drives, memory cards where Fat may be the default file system present.

When having one WD drive external turning out to be a GP sata II model drive enclosed in the drive saw exFat and had a form of Readi-Boost app that would bring up an installer. The installer was needed for Vista not XP or 7! I simply cleaned the drive off totally while booted live from a GParted Live cd and put a brand new NTFS partition on it.

If you already tried using the DiskPart tool and still got nowhere as far as the wipe and clean ntfs partition created the live cd option would be the next step. If that still fails you could be looking at a bad drive needing to be replaced or simply returned. Or the factory Partition Table was corrupt when you bought the drive where a full wipe is needed.

Are you plugging into a USB 3.0 or 2.0 port? The images show the Disk Management prompting to select either the MBR(Master Boot Record) or GUID option in order to see the drive initialize. That's a normal prompt where you decide if you will ever want to make it bootable or simply see a new Partition Table created.

From there you should be able to create a new volume on the spot! Look over the images attached to see how that works.

You can use the snipping tool in the Start>Accessories to grab images if you want rather then the need to attach pdf files. But the first thing to look at would be in the Device Manager under storage devices to right click on the drive item you find there to see if Windows will automatically search for and install the controller driver needed for you.

Lately I had to coach someone else who received an external enclosure as a gift on how to debug a similar problem of seeing the necessary driver go on Vista not 7 however. Checking for updates manually and looking at the optional updates might see the update you need included there or running the Secunia Personal Software Inspector would be an alternate route to take to see this cleared up for you.

Have you looked under Storage controllers? You should see the manufacturer's name listed right away. Once the drive is initialized provided it is working as it should then you should see it appear under the Disk drives.

With one external drive without it actually having problems but having the need for an extra drive during the 7 beta/RC days I simply pulled the drive out of the enclosure to install internally and called it a day. If there's a controller problem which doesn't seem so likely or you can extract the drive carefully long enough to connect it internally if there's no eSata option you would find out if the drive itself will work or need to be replaced.

Here that old 500gb external is now presently the internal storage drive on the old Vista case rather then putting it back into the factory not so well vented casing. I have a fan cooled enclosure for any external drives instead!