Advice on how to start my son off in Flash

I’ve got an 8 yr old son who loves playing computer games and designing games on paper.
I am a professional programmer using visual basic mainly for .net web applications.
I am keen to introduce my son to simple programming, but to be honest is going to be very boring introduction for him and I don’t want to put him off.
He likes playing flash games online, but I have zero knowledge on how to go about starting him off with helping him write simple games and learning programming.
I have got experience in writing games a long time ago in Basic and machine code on older machines, so think I could help him along.
I think Flash could be the way to get him started.

My question is, what do I need to get to start him off from the very beginning in writing simple games and learning how to program in Flash?
I really have no knowledge, so any help appreciated, eg what software editor do I need? Any good books? etc…
Just nice and simple stuff to begin with such as pong or snake or any old basic games hopefully to give him the bug. I love programming and I’d like to get him hooked too (good job prospects for the future…)

Many thanks