Yes... the first time I tried to load a *.dbf, it wasn't even listed in the file extensions list as in Joe's picture. I followed my suggestion rather than wade through the windows 7 stuff.
This process has worked in all previous incarnations of windows that I think of. It is a useful idea, should you wish to create your own file extension and have it loaded by a particular program.
Effectively, you would be the only one that could load it easily since the extension wouldn't appear on another person's machine as being able to be opened by anything. Very effective for binary files... providing an extra level of security to slow down the 12 year old for an hour or so.