UnionFS alike on windows, Virtually merge folders

Scenario: You have 10 hard-drives (A...J) across three computers (Alpha Beta Gamma) all running ... say windows 7. Lets say that these drives each have a folder for /Music /Movies etc across them all.

On Linux with UnionFS I was able to map a local share on say my computer Delta say... /Music which would be Read-Only and would contain all 10 drives' /Music directories.

Is there a similar software package (preferably with a Gui) which could give me this same flexibility. So that on Delta I could go to Z:/music and see the culmination?

This does not seem like an unlikely scenario and I'd hate to dedicate a Linux box to merging all those drives and then sharing that folder so that my windows laptop (Delta) can have something nice and clean to access.

Windows 7 has introduced the concept of Library, which is functionally somewhat the same as UnionFS. From How to Use Windows 7's New Library Feature:

You could say Libraries are virtual folders. You add folders to Libraries, where you can view and access the contents of each added folder from the single Library window. A Library itself can’t contain any files as they aren’t real folders, but they offer one-stop access to a collection of folders.

Here are several ways you can make use of Libraries:

• Add folders that are scattered throughout your hard drive(s) to Libraries.
• Create custom Libraries. For example, when I start a new writing assignment, I can create a new Library. I could add related folders such as the one that contains the publication’s guidelines, folders on previous work that I think I’ll want to reference, and folders containing any downloaded research.
• Add network locations (shared folders from other computers) to Libraries.

For some more detailed info, see:

Windows 7 Libraries .NET Sample Library – an Overview
Understanding Windows 7 Libraries

As your example you mentioned running Windows 7. There is a built in feature called libraries that creates a virtual folder that combines the content of several folders.

There's a howto on technet that you can watch to get some more information on how to configure libraries.

Libraries in Windows 7 aren't read only. The first folder you add to the library is designated the default save folder. If you try to write something to your library it will end up in that folder. You can change this in the properties for that library if you want to save to another folder instead.

I don't know of similar software for other Windows versions though.