When it comes to protecting folders with passwords, there are many handy software tools you can use. But what if you don't want to install another program on your already crammed disk just for that? Don't worry, there's also a way to protect folders in Windows XP without having to use third-party applications.
Right click on the folder you want to protect and select Properties in the context menu. Then click on the Sharing tab and enable the "Make this folder private" option.
The folder will be automatically protected with your Windows username password. If you don't have one, the system will show a message asking you to create one right away.
Also, if the folder you want to protect is zipped, you can also assign a password to it without installing any additional apps. Open the ZIP file using the Windows native ZIP file manager, click on the File menu and select "Add a password". Windows will display a dialog box where you can set the password for that zipped folder.