How to create a Windows Explorer extension

Hi experts

I'm not sure if i've titled the question properly.  What I'm wanting to do is to create an extension to Windows Explorer that will allow me to browse some particular device as though it was a folder in My Computer.  For instance, Siemens phones and Symbian devices both have an icon in My Computer that, when double clicked, they open up a window VERY SIMILAR to windows explorer (although isn't actually windows explorer).

I would rather be able to do this with either VB.NET or VC#.

Am not really looking for specifics (although they would be really appreciated).  More, looking for pointers, or how it should be done in theory.

Any help would be well received.

Thanks in advance.