Using WinXP? In general, you can't. Access to folders is controlled by
permissions granted to user groups IF using NTFS.
If using FAT32, use a third party program to lock down folders.
*.ZIP files can be password protected using XP's native zipping
capabilities. However, you would need to zip entire folders (being careful
not to zip profile folders that are accessed by the system for normal
operations). Then use the *.ZIP file's properties to add a password. This
is not the most convenient or practical method to use for controlling
folder access.
