You can use the encrypting feature. According to Microsoft, Encrypting folders and files is a way to protect them from unwanted access. Encrypting File System (EFS) is a feature of Windows that you can use to store information on your hard disk in an encrypted format. Encryption is the strongest protection that Windows provides to help you keep your information secure.
Unfortunately it is easy to gain access using the default windows password ***** (you can just remove the harddisk and connect it to another computer as storage device and access all the files and folders; or, you can just create a bootdisk to bypass the window password *****) that's why "encrypting the files" option is the best option.