I'm working with Reading Greek An Independent Study Guide, (1st Book) Reading Greek Text and Vocabulary (2nd Book) and Reading Greek Grammar and Exercises (3rd Book)
I have the audio that goes with this set too. You have to have the three books to make much of it.
It is absolutely the best course though, done by Cambridge University Press.
I have Parr's and White's books, have studied from White's book, but it is still a difficult language to learn.
I have made an electronic copy of John Williams Whites book, although it is not perfect, (I am revising it once again . . . adding accents, circumflexes, etc.) It is not readable by Textkit though, I created a program of my own, called Tachufind, which was made specifically for learning Greek with JWW's Book, using colored text to find grammar or highlight definitions. If you want to check it out, it is on my website at http://www.tachufind.com
, and it 100% free. James Williams White's book is also there for download, but as I said, it is not perfect yet, and I am working on getting a better version ready. The advantage of having a text copy of the book is that you can search it.