What we found

There wasn't a lot separating the top 6 products and any of these filters will provide a good level of screening. Each blocked 100 percent of pornography.

The top two programs, NetNanny and Integard, offered the best combination of performance, ease of use, flexibility and useful extra features. Both blocked 100 percent of the pornography we threw at them, but were less effective with guns, crime and terrorism.

The best free program, Parental Control Bar, was the most successful filter in our test. It blocked pornography, abuse and guns completely, and was very tough on violence, drugs and hate speech. It wasn't as flexible as the two top programs, but it blocked more content - and it's free.

All the filters except Parental Filter were effective in blocking at least 90 percent of pornography. Terrorism was a weak point however, with no program blocking more than 53 percent.

It's worth noting that all the programs tested have the potential to perform better if 'trained' correctly over a period of time by manually approving or disapproving content. This was easy to do for all the programs we tested.

Net file protection only

Good net filters can help protect you from offensive content detected live online, but won't protect you from the same content loaded from other sources.

We downloaded a .zip file containing restricted material, extracted the images to a folder on the Windows desktop and on to a USB key, then in both cases viewed the images from within a web browser.

None of the filter packages blocked the test images when loaded from a 'local' source rather than directly over the internet.

Updates and specifications

All the net filters tested included an update feature to provide ongoing protection, but Parental Filter, Cyber Sentinel and NetMop couldn't auto update. Not surprisingly, automatic updating is easiest to use. Each time you load the software or turn on the PC, the software is able to check for new information on restricted content, and immediately download updates.

Manual updates require the user to remember to check for updates and initiate the process through a menu selection or via the developer's website. The risk is that unless you check regularly, information that the software relies on to detect bad content may become out of date and reduce your protection.

Browser and system support

We-Blocker and NetNanny 5 didn't work with Firefox. All the filters except CYBERsitter worked with Windows 2000 and XP. All except We-Blocker, ParentalControl Bar and Cyber Sentinel worked with Windows Vista.

Multiple computers

NetMop, Integard and Filterpak come with three licences and are the only tested products stating they can be installed on more than one PC. NetNanny 5, CYBERSitter, CyberPatrol and Cyber Sentinel require extra licences to be purchased and installed on any additiional machines.

All the free filters could be installed on multiple computers, but required a unique email address to be entered during the registration phase of each installation.