Windows 8 itself
Running Windows 8 on a PC or virtual machine will help and its not too hard to set up. I have been working through the book below over the last couple of days, and it is invaluable to be able to jump out into Windows to try a feature when you get to it in the book.
There is a growing range of Windows 8 books available, via Safari Books Online I have been using and recommend Paul Thurrott and Rafael Riviera’s Windows 8 Secrets. (John Wiley & Sons)