<Coughs> Erm...my two daughters (12 and 9) have unlimited access to their own intenet connected PCs in their own rooms 24/7 !!
The eldest spends hours chatting to friends worldwide (esp USA) and research for homework (true).
The youngest goes for car racing games but soon gets fed up. Her reading and spelling have been transformed though.
Both regularly listen to online music stations (esp Capital Disney) whilst playing or reading.
I trust them both and rarely find virii or trojans etc. from 'odd' sites.
Unfortunately where we live they don't have any friends locally.