Don't let your children read Harry Potter. I read six out of seven Harry Potter books before I became Born Again and completely stopped.
The Harry Potter series introduces children to witchcraft, it promotes witchcraft. Once children have read these books they accept witchcraft as J.K Rowling presents it: a whole lot of fun - that there is absolutely nothing wrong with it. How can children be brought up with a Biblical foundation when they are taught to accept what is an affront to God?
Deuteronomy 18:10
10 There shall not be found among you anyone who makes his son or his daughter pass through the fire, or one who practices witchcraft, or a soothsayer, or one who interprets omens, or a sorcerer,11 or one who conjures spells, or a medium, or a spiritist, or one who calls up the dead.12 For all who do these things are an abomination to the LORD
Children need to be brought up knowing that all power comes from God alone and that any power that is not from God (magic), even if portrayed as inherent, or 'good' is from Satan and an is utterly wrong.
It's true that Harry Potter doesn't directly mention Satan but that isn't the point After I read it, I was instantly more open to that genre, ready to accept books, games and movies with a heavier emphasis on magic that would sometimes have definite occult/pagan influence. The danger of exposing children to these books is the world that is instantly opened to them, a world of witchcraft that they understand as being good.
Furthermore, what happens when children move on to the teen fiction sections, they find Wiccan propaganda in books such as 'how to be a teenage witch', the book is actually serious guide on how to become a Wiccan and do witchcraft of your own. After this they can move on to the non fiction section of any good library and find complete guides on the occult.
The danger of Harry Potter is that it is a guide, it and all the other media masquerading under the guise of innocent fantasy, a guide that is steering children to Satan, corrupting their minds and unbelievers can't see that, just look at all these answers... don't listen to them - listen to God's Word.
As a responsible mother, how about showing your children the verses I quoted and then explain to them that that is exactly what Harry Potter promotes, sin. Once they know and understand that it's wrong, they won't read the books even if they find it, especially if you can teach them the truth about witchcraft at a young age, they won't forget it, this is a lot more powerful than simply forbidding it.
Of course, this will also earn them the ridicule of their friends as I did from mine, I guess the best we can do is pray and trust God to give them the right friends, God answered that for me too! So don't worry, God will take care of your children too!
To tell you the truth, there's so much of the world around that I've found to be influenced by the occult that I've changed a lot of the things I read, watch and play quite a lot, and I've had to make those decisions, as hard as they were - all thanks to God and of course my mum and pastors. From experience, just teach your children and pray for them and as they grow more mature in God they will learn to discern between good and evil for themselves, because we certainly need to be able to in today's world.
I'll make sure to pray for you and your children,
GOD BLESS YOU!
Please have a look at some of these sites that I've collected, they should provide more insight about Harry Potter and also some other important topics.
http://www.bible-knowledge.com/Harry-Potter-and-witchcraft.html
http://www.cuttingedge.org/NEWS/n1390.cfm
http://www.carm.org/more-stuff/features/pokemon-what-it
http://www.pastornet.net.au/response/articles/41.htm