Most people with a iPod don't know you can use it as a external hard drive, but you can. Windows sees the iPod as a USB mass storage device and mounts it with a drive letter. Your music file are in a hidden directory structure can easily be accessed.

The Microsoft Zune can't be accessed in the same way. It is it's own device and not accessible. Well, so we all thought.. Some industrial folks have found a way to enable pseudo hard drive support. It doesn't get assigned a drive letter, but does allow you to drag and drop files from it.

Turns out it's just a registry value to enable visibility in the shell. 

Here are the instructions:

1. Make sure your Zune is not plugged in and your Zune software isn't running
2. Open up regedit by going to the start menu and selecting "run". Type regedt32 and hit "OK"
3. Browse to HKEY_LOCAL_MACHINE\System\ControlSet001\Enum\USB\
4. Search for "PortableDeviceNameSpace". This should be contained in the Vid_####&Pid_####\########_-_########_-_########_-_########\Device Parameters within the above ...\USB\ The ##'s listed here will be numbers and letters specific to your Zune
5. Change the following values: * EnableLegacySupport to 1 * PortableDeviceNameSpaceExcludeFromShell to 0 * ShowInShell to 1
6. Plug in your Zune, and make sure the Zune Software starts up.
7. Hopefully at this point you can open up "My Computer" and browse your device, though it does NOT show up as a drive letter.