When you have kids and they like computers and stuff, they also might like to do some more 'What daddy or mommy does'.
And actually they can 
. I stumbled into KPL, a Kid's Programming Language, which makes it really easy to teach all types of things you need to do when programming, such as variables, loops, decision structures etc.
And as a Plus, the IDE, which is also provided, really looks a lot like VS.NET.
So when they grasp the concepts and the IDE they can easily 'graduate' to your favorite .NET language...
Have a look over here if you're interested...