Hello MR user, this is the solution to this problem, in case you want to transfer books to your apple device you need to do the following steps:
1- you need to download an application from the itunes store , the name of the application is Bluefire, this is a free application to read adobe DRM books (like the books from sony store).
2- ones the application is install in your apple device you need to complete the registration process with the application, it will ask you for an adobe ID which in this case will be the same ebookstore email and password.
3- now the application will be ready to open books
To transfer the books from the computer to your Ipad you need to do the following steps:
1 - using your email you will attach the epub file (this is the format for the ebookstore books) to an email that you will send to your self, I will recomend you to transfer 3 files per email, in this way you are transfering the books to your device, because the apple device will have your email set up so the email will be in your inbox in your device .
where the books are save in the computer :
- windows XP : mydocuments/mybooks/reader/books
- windows vista or 7: documents/mybooks/reader/books
- Mac: user/documents/mybooks/reader/books
2- ones you receive the email in your device you will be able to open the files on your device by double typing in the file icon and select open with Bluefire.
3 now the application will open and you will be able to read the books.
In my opinion this is the easies way to transfer the books from the computer to the device , you need any other software in your computer to do this just your email account and your with your email account set up as well.
let me know if you have any questions