I've used windex a lot for my screen, and I've just learned that it can allow for scratches. I always get a lot of smudges on my screen too. I had recently bought a silicon case for just the back and edges of my ipod, and the screen protector it came with was a piece of crap. Should I go for the invisible shield, while its on sale, or buy a different screen protector, like the one from apple? I want a good quality one that I can use for a while.