Well, I let my 7 year old watch me install stuff, and when I got his new motherboard, he got to choose one out of 3 780G boards I showed him at Newegg. I had a spare X2 4200+ for it, plus legacy DDR2 667.
When the board arrived, I showed it to him and let him touch the board's static bag, then he sat down and watched me install it and set it up. The thing I'd forgotten was that it only had one IDE, so I put in an IDE card for the DVD-ROM.
Anyways, he wants to build his own PC's and I told him he'll have to watch and study until he's 12 or 13. Then I'll walk him through a build. Plus, I'll send him to camp so he gets his A+ certification in junior high or early high school so he can have a better job than retail over the summers.