If you want to be green and save paper you might think about getting yourself an electronic book reader. There are a number of different ones available today, but I think that the new kindle from Amazon is far and away the best. It’s just so much more convenient as you don’t have to download to your PC first and then transfer - it comes straight from Amazon via 3G communications to the device. Also, a lot of the other books will need you to download not just the book but special “library” software to control the storage and reading of your books.