Windows Vista Service Details
Allows you to have protected storage, like in your home folder. If you have multiple users accessing your computer, and you do not want them monkeying around with your files, then enable it. If you are just one user, I see no real need for it.
Provides protected storage for sensitive data, such as private keys, to prevent access by unauthorized services, processes, or users.
Consequences of Stopping:
All services listed in 'Required For' will be unable to function