What Is It Capable Of? Options

I'm relatively new to the serious study of magick. I've been reading some of the works of Aleister Crowley, Gerald del Campo, and other thelemists. After reading about thelema, I'm left with the distinct impession that magickal workings are, in practice, essentially useless. All of the claims of "magickal" happenings seem to be spiritual and introverted in nature. They seem to be a means to better understand one's self, much like buddhist forms of philosophy and mysticism. Here is what I want to know: What are the actualy practical applications of magick? Is it possible for magick to effect dramatic, tangible change in a subject outside of the practitioners own mind? What kind of changes can be observed?

...I've always been of the opinion that if you have to imagine something, it probably isn't real...

Imagination is the seed of creation. Most of the things we see around us are the result of imagination. There once was no such thing as cars or airplanes, someone imagined them and now they are real tangible things. The concept is similar in magic with the exception that an idea or intent is made to manifest through unseen forces rather than physical ones. I believe that the most simple example of this is the fact that imagination exercises used in psychology do have a direct impact on the ability to change ones self. With a little more work and intent this can be made to manifest change outside of the mind.