I don't want the screen to get scratched since it's the most important part of the iPad, so I would want a screen protector. Is there one someone can recommend? One thing I'm confused about is why people here don't use screen protectors. I noticed many people here say it's because it ruins the "retina" or something... but I'd rather have the screen protected regardless. Also, I would want one for the back too. But is the screen protector strong enough to prevent scratches?