I'd let my kids on the net.
most kids, by the age of ten, aren't stupid enough to click ads. the majoruty also still thinks a naked women, is gross.
Would I watch him? not really. I'd pass by every now and then. he's only ten.
I'd trust him well enough to do what he wanted to, but if I ever found a serious problem, like he was making a bomb or drugs, I would shoot the computer.
as for porn, as long as he knew what he was watching, and didn't get......hooked on it.
I would prefer that he didn't see porn at all, but depending on the level of it, I would more have that, father-son talk.