Windows Live Family Safety is a good, free Windows program, that is part of the category Security software with subcategory Blockers & Access Control (more specifically Internet) and has been created by Microsoft

PicBlock is a good, free software only available for Windows, that belongs to the category Security software with subcategory Blockers & Access Control (more specifically Internet). It's available for users with the operating system Windows 98 SE and former versions, and you can download it in English

Port Locker is designed to add an extra layer of security to your computer

HomeGuard Activity Monitor is a powerful computer monitoring program that can be configured to protect children of all ages

Winlock is a complete program designed to prevent prying eyes from modifying, viewing or configuring elements of your computer that you would prefer them to leave alone

SecretFolder is a simple way to achieve something that many of us wish our operating systems did more easily; create a private or hidden folder

Matrix Screen Locker is a small but effective application that makes protecting your PC an easy task

Let's make this clear right off the bat

PC Locker Pro is an amazing, free Windows software, that is part of the category Security software with subcategory Blockers & Access Control (more specifically PC Access Control)

DNS Angel lets you modify the DNS server used to access the Internet by replacing the ones from your provider with those of Norton ConnectSafe, Open DNS Family, or MetaCert DNS

Program Lock Pro is a nice, trial version Windows software, belonging to the category Security software with subcategory Blockers & Access Control (more specifically Specific Applications)