There are many ways to keep your PCs confidential files safe from snoopers. You could encrypt them individually. Store them in a password-protected archive. Maybe just bury them deep in some unexpected area of your file system.
Anvisoft’s Anvi Folder Locker Free aims to simplify the process by applying protection at the folder level. In just a few seconds it can hide a folder, add password protection, maybe just make it read-only – whatever suits your needs.