[st0neage]

Don't. The (programming) world isn't perfect and trying to protect him from anything "confusing" or bad will not help him in the long run. Instead, explain. If you don't have a good answer, research the reasons. Getting to know and working around (or with) the quirks of the system is important. Don't take that away from your son.

[sdegutis]

I generally agree with that point. That's why I'm starting him off on QBasic. Actually if I can find a good graphics library for it, I might teach him Julia next.