Children as young as 6 or 7 are now as familiar with the computer and the Internet as they are with their toy cars and dolls. With popular social networking sites such as Webkinz, Club Penguin, and MinyanLand drawing in ever-younger kids, parents are often left scratching their heads as to how to regulate an entertainment medium that just didn’t exist when they were young.

Although you may be confident that you've installed parental controls, and that your pre-teens can’t stumble across anything too objectionable, you may still be looking for a “code of conduct” when it comes to how much time your kids spend front of the computer. Here are 6 suggestions to help set the rules when it comes to your younger children’s virtual world:

1. Include the computer in their total screen time. Whether they're allowed one or 2 hours of screen time a day, don’t forget to include time in front of the computer (and time playing video games!). Time spent on Internet sites adds up very quickly and, before you know it, your kids have been staring at screens for 3 or 4 hours!

2. Don't allow computers or TVs in kids' bedrooms. Keep the computer in a family area. Your kids will see using the computer as a family activity -- and you can keep an eye on them!

3. Be interested in what they're doing. Whether they're playing games, networking with friends, or just browsing National Geographic Kids, show an interest in what your kids are doing. Just as with their homework and sports, if your kids know you're interested, they'll take it more seriously and try to please you.

4. Teach them to protect their identity. Just as we teach kids not to talk to strangers, we should also teach them to not give out personal information over the Internet. Make sure they use passwords and only interact online with people they know off-line.

5. Explain what inappropriate behavior is. It’s never too early for children to learn how to be respectful and polite online. An early understanding of email and social networking etiquette will carry over to their later years and help protect them from being cyber-bullied or becoming a cyberbully!

6. Set a good example! Like almost everything else we do to raise healthy and well-adjusted children, setting a good example is perhaps the most important contribution we can make. If you don’t want your kids to spend too long in front of the computer, then make sure you’re not spending hours there, yourself. Don’t like it when they're constantly playing with their DS? Then think about leaving your BlackBerry (RIMM) or iPhone (AAPL) behind when you take them to soccer -- or even when the family goes out for dinner!

Monica Vila dispenses more tech advice for parents at The Online Mom.