I like the idea of building your own computer. Maybe do a weekly update type thing. That way it takes a while and brings people back often to check for updates. But do more than just showing how to plug it all in. Show how to install an OS onto a new drive several ways(bootable cd, creating a boot disk from scratch, etc) yada... yada... yada...

"Please, Please do not push the button, You have no idea what it <boom> ...does"