To Start Programming

My 13 year old son has never been that interested in phones or computers, being the outdoor adventurer type. But he needed a laptop for school so he recently got a Windows 8 laptop. He's now showing a great interest in computers.

I thought I'd seize this interest and maybe start him learning some programming. It's a great thing to learn, and with an increasingly IT world may become more essential. But where do I start? I started to learn ARexx (http://en.wikipedia.org/wiki/ARexx) when I was a teenager, but I never got very far and that was 20 years ago. So I have no experience in this at all.

Any guidance on where to start, programs to use, books to buy, websites and forums to frequent would be greatly appreciated.

Cheers guys