ok... here's what I was able to find (and it's based on the same site you quote):
"...that there are several cases of possible influence from Crowley on the book, including actual quotes on magical theory from Crowley's own published works; words or symbols associated with Crowley; and parts of some rituals. However, it is equally clear that Crowley would not have written it; for one thing, "Ye Bok" doesn't spell magic with a "k." As Dearnaley says, "If Crowley himself had written it, he would surely have titled it something like The Art of Magick, vel Liber XL (or De Arte Magica), not Ye Bok of ye Art Magical."
I'm pretty sure there's actually no serious doubts that Gardner wrote this book, and I'm also pretty sure that the original manuscript is currently at the Wiccan Church of Canada. There are some relevant historical facts: Gardner is known to have been familiar with Crowley's writing as well as meeting Crowley himself, though after, not before, he began investigating the occult. "
There are also worlds of difference between how most Wiccans today practice, and how Garndner parcticed (much like the differences between early Christians and modern Lutherians).
Now I think we've taken this thread far enough off topic...