FFGuard

FFGuard is a secure and easy to use program that lets you password-protect and easily prevent access to your important files and folders that may be your privacy. It can lets you specify which programs are still able to access protected items, such as virus scanners or disk drive utilities. A protected folder and its contents will be prevented from being renamed, modified, deleted, copied, moved, accessed or even seen on the system. Version 2.01 may include unspecified updates, enhancements, or bug fixes.

Requirements:

Windows 2000/XP/2003 Server

Limitations:

Can't change the password