Aeon418
Very good book suggestions. I'll add "The Magick of Thelema: A Handbook of the Rituals of Aleister Crowley" by Lon Milo DuQuette.
Which was revised and retitled in 2003 and now goes by the name of, "The Magick of Aleister Crowley: A Handbook of the Rituals of Thelema".
http://www.amazon.com/The-Magick-Aleister-Crowley-Handbook/dp/1578632994
It's a good book*.
*Caveat: Despite several flaws and inaccuracies in his presentation of some of the rituals.