The Loss of Childhood.

When I was a kid, there were certain TV programs that I wasn't allowed to watch. Not that there was something so horrible about them, that I couldn't see (remember, those were Soviet times) but mom and dad simply told me that they are "not for children"! Today... can you tell your 4 y/o not to watch something? Your kid will look at you as if you've got a screw loose. And what is suitable according to "latest research"? I won't let him see "Kill Bill", that's for sure, but is a western okay? Is it too violent, or does it show the "good old values"? Can he see science fiction, or is it too scary? Should I limit him to jumping teddy-bears, or can he see the 8 o'clock news?