Greg,
I did a clean install of the OS when I got it. Then just added two free security programs. Surpisingly the kids have not taken to much interest. My wife told them it was not ready and they have left it alone. Heck, maybe they will not destroy it after all.
I planned on not backing it up. If it gets too messed up I can just reinstall the OS.
But I have enough issues with this Vista machine, that I am not evn looking at the old one.