How do I increase the security and privacy of the computer that my child uses?
Before you tackle the computer, talk to your child. It is a good idea to set expectations for online behavior and then monitor what they are doing. Make sure your children know that people on the Internet may not be whom they say they are. Teach them to never give personal information to anyone. Be sure they understand that messages or pictures they send are not truly private or anonymous, and that friends might forward them to others.
For security, use one or two anti-spyware programs in addition to your anti-virus software, and keep them up to date. Norton by Symantec and Kaspersky Labs are two popular choices for antivirus software, and it can be downloaded right from their websites. In addition, install and use a firewall. A software firewall is built into Microsoft Windows and all anti-virus software companies also make them, as well as specialty firewall vendors.