Hi, Bob,
This is properly a question for a Windows newsgroup rather than Word.
Anyway, the answer depends on what version of Windows you have, and how your
hard drive is formatted. If you have Windows 95, 98, or ME, the answer is
no. If you have Windows 2000 or XP, *and* your hard drive is formatted with
NTFS instead of FAT32 (look up these terms in Windows Start > Help if you
don't understand them), then you can use the folder's Properties > Security
dialog to set permissions. The Windows Help topic "To set, view, change, or
remove file and folder permissions" describes the steps.
The permissions and passwords are on a per-user basis. That is, if someone
logs in as you with your password, or as a member of the Administrators
group, they will have access to the folder. If they log in as another user
or as Guest, they won't have access. Windows doesn't challenge you or ask
for a password when you try to open the folder, it just denies access if you
don't have permission.
If you use Google, you may find some third-party programs that
password-protect or encrypt folders even on Windows versions that don't
support permissions.