Mine has had his own since 2.5. We didn't buy it, it was DH's old computer. For a family of 3, we now have 6 computers :-0.

People may disagree but he also has completely open internet. I spend a lot of time watching him, discussing ads and ad placement and how you can tell if it's an ad. We talk a lot about how to search on Google, what is an appropriate search and how to use operators to make sure you get what you want. He is not allowed on youtube without me looking over his shoulder. He knows I check his history and any transgression results in immediate loss of computer. His computer is in our home office so I can pretty much always see what he's doing.

Worst offense so far at age 8? Finding, then begging me to get him a Wizard 101 account :-)