I was thinking the same thing when I was younger - when I left primary school I was wishing so hard to get a Hogwarts letter that I actually believed I would get one! I was so dissapointed when it never came and I got sent to my secondary school instead.
Being brought up by a Christian family, I have always believed that there is more out there than what normal people see day to day. But whatever the explanation for all the unexplained things in the world, I don't really believe that a world like HP exists. You can never rule out the possibility, but I doubt it is.
Looking at the books logically, they have all the coincidences and plot tricks that would appear in fiction, not real life. In real life, what are the chances of Hagrid finding out Harry has the Invisibility Cloak just in time to sneakily show him the dragons? In real life, what are the chances of Trelawney seeing a death omen that looks exactly like Sirius' Animagus form, just as Sirius has escaped from Azkaban and Harry's spotting him all over the place? In real life, wouldn't Umbridge have been put on trial for using an obviously Dark method in detention? And so on. Not to mention, from the psychology point of view, Harry would probaby have had a nervous breakdown before he even heard of the Triwizard Tournament. Of course, you could always argue that JKR changed things to make it a more exiting story.
I suppose it comes down to whether you believe magic exists or not. The things about the hurricane and the news about Sirius Black, could have been covered up if the world really existed, but I don't think it's real.
Personally, I hope it isn't - I want to be an author myself and JKR's genius was what inspired me. Learning upon the release of DH that I had been reading too deeply into the books was a letdown for me - if the world never came from her head in the first place, it would be an even bigger letdown.