fractal, you absolutely MUST read Valis!!
Also the book A Scanner Darkly might grab your attention more than the movie. I have to say I only got really interested in the movie after I had a feel for PKD in general. The tragic and tortured nature of his characters and the loss of sanity that is pervasive throughout most of his stories just grabs me. A Scanner Darkly is no exception.
The name is derived from the Bible, "For now we see through a glass, darkly." - referring to our perception, which is of course one of PKDs main themes. Reality, perception, insanity... I was very moved when I read the book (A Scanner Darkly, not the Bible). The movie was good, but the book was what made the impression, even though the movie is extremely close to the book.
man, this makes me want to read more of his stuff...
cheers,
Enoon