@Turtle: Microsoft have a problem
This is one of the many reasons I don't like applications like iTunes which force you to work in certain ways with Albums, Genres, playlists etc. I sort my music into folders depending on various things (sometimes it's dates - for DJ tracks, sometimes it's albums, sometimes it's genres) and I have an MP3 player that allows me to play back using this format as well. To reorganise this into playlists and so forth would be a mammoth task.
Databases have their place but I think it would take some getting used to, if trying to move away from a standard filesystem format which is tried, tested and generally works.
That being said, I use GMail and barely do any e-mail sorting. I can find any e-mail I need from the last few years practically instantly. This pleases me immensely.
A file system that allows you to apply organisation structures but also instant search would be very nice indeed, but would probably require some serious adjustment from a user perspective. That said, many people are used to using iPads and so on and are completely "protected" from the underlying file system!
Personally I agree with @ForthIsNotDead. Windows is a great operating system overall, and is definitely unrivalled in the workplace for management etc.