While I agree with the above writeups in the fact that Harry Potter does garner virtue by introducing children to the power of reading, I don't believe this argument fully dismisses the "occult" accusations. While I personally don't believe that Harry Potter swings kids torward witchcraft, simply saying that the books are a needed break from Nintendo Co. and vapid TV shows doesn't counter the specific argument that the books makes kids want to sacrifice Rover to the Dark Lord.
Interestingly enough I've noticed that people who accuse the book as being "evil" are simply looking at the setting, not the context on which witchcraft is being used. Harry Potter's world is whimsical and playful! He and his two friends Hermione Granger and Ron Weasley aren't making pentagrams with salt and channeling evil powers, they are eating chocolate frogs, ingesting Floo powder, and simply being inquisitive, normal children who just happen to play Quidditch and save the world. The good people in the book are presented as moral. Harry Potter and Co. may stir mischief against the school authority, but it is all done in a light-hearted Little Rascals-esque style. Although not a central theme to the book, religion does seem to have a place at Hogwarts: Christmas and Easter are both celebrated (although Jewish holidays have yet to be mentioned).
One theme that permeates all religions, including Christianity, is the idea of good against evil; and both powers being separate entitites. This is also represented in the Harry Potter novels; some wizards, like Albus Dumbledore and the Gryffindor headmistress, Professor McGonagall, are allied with the Ministry of Magic. The Ministry's goal is to enforce the use of magic for good causes and for the betterment of humankind. Others, like Lord Voldemort, are considered evil, and want power to themselves. The "good" people use the powers of the supernatural, but is this necessarily a bad thing? There are many instances of supernatural powers being used by Jesus Christ in the Bible: turning water into wine, raising Lazarus from the dead, and healing the blind aren't exactly every day occurences. Most religious texts are no stranger to phenemonal Might for Right.
Now, if these novels did not have the witchcraft element in them at all, would there even be an issue? Most kids with a healthy dose of common sense would realize that a Nimbus 2000 and a magic wand are not in their future, whereas the theme of good triumphing over evil is universal, and something that relates to the real world. The people who dismiss the novels are not only depriving their child of a wonderful, imaginative experience, but showing that they mistrust their child's ability to differentiate between fantasy and reality. They are also expressing a doubt that their day in, day out influence can overpower that of words on a page. If there is a legitimate concern about the "occult" nature of the book, a good talking-to before the child reads is probably all that is necessary for the child to get the idea and secure any parental qualms.
To all of the Christian fundamentalists, I say "Read the book!" Don't let Jerry Falwell-esque propaganda cloud your better judgement.