Hi Susan,
Welcome to Syschat.
Good starting point in cleaning and updating your computer is
explained in this article (
Secure your computer from viruses and spyware for free)
After you done with doing things in above article, install and run
RegScrubXP Free Registry Cleaner and
CCleaner RegScrubXP will clean your registry, and
CCleaner will remove unused and temporary files from your system.
And regarding protecting/controlling your kids you can try this free software called
Parental Lock Guard and also there are plenty of commercial/shareware parental control software's available on the internet.