1.The Eleaning modules (for E20-001) that you can purchase through Powerlink are really good for this one. What you can do is when you connect to each E-learning module, you can save the Student Resource guide for each module in PDF format. These go into more detail than the E-learning modules (the PDFs are attached to the E-learning modules). There is alot of reading to get through, about 800 pages if I remember, 7 sections.
2.Or the other option I think would be: http://education.emc.com/ismbook/
When I took the exam, this book hadn't been released, but I've flicked through it, and I think it will help alot.
3.Make sure you also have a look at the E20-001 "Exam description" :