With password protected sharing enabled, other computers on your network will not be able to access your shared folders, including the Public folder, without a user name or password that corresponds to a user account on the computer with the shared folder. Check out the site for yourself, there's a lot of information on setting up File and Printer Sharing between Vista PC's in a Workgroup environment. The information below was found on this site.
If the same accounts exist with the same password on each of the computers, you should be able to use password protected sharing.
