I recently read a very interesting post on Jeff Atwood post: Filesystems Aren't a Feature. He starts pointing out an observation done by a developer watching his relatives using the pc:

When I observe how my wife and son uses the family computer, I can't help noticing how little use they have for the desktop. They look bewildered when I open the Windows Explorer. To them, file open or file save dialog is where the files go. My Documents? It's just an icon they never touch.

I don't even know why the open dialog (and the save dialog) and the File Manager (Explorer) should be different. They have the same function: locate a file. In his post Jeff consider alternatives to the direct exposure of the file system to the user. I agree that the File System hierachical structure -with files, folders, and different partitions- is confusing, but we should wonder in the first place why open/save dialogs ("where the files go") is different from My Computer. If they were identical, sharing the same interface, would it be so confusing? I don't think so..