I love the Harry Potter books and movies. They get down to the basics--good vs. evil. My younger brother got me hooked on the books. I come from a family of avid readers and it's wonderful the way my brother (who is 16), my dad (who's 52), my husband (27) and I (24) have read these books and can talk about them.
They appeal to a wide audience and I don't understand how they lead to Satanism. They are very clear-cut on what's good and what's evil. Also, they are quite obviously fantasy. If magic leads to Satanism, then also don't let your children hear fairy tales and by all means, don't let them watch The Wizard of Oz or Jim Henson's wonderful movies Labyrinth and Dark Crystal. Even the Care Bear movies have magic....
I worked at a Catholic daycare at my parish and all the children love Harry Potter and, amazingly enough, understand the difference between fantasy and reality and are still good Christian kids with no thoughts toward Satan. Children are incredibly bright, let's give them and their parents some credit.