I don't know if I explained myself adequately in the above thread.
What happens for me is that after I have bought an Epub book, from any where, I then open my Sony Reader on my PC and go to File, Import Files.
You'll find the book in which ever directory you downloaded it into when the site you purchased it from delivered it to your PC and you downloaded it.
The Sony Reader will allow any Epub file to be downloaded - DRM and non DRM.
After I've downloaded it to Sony Reader I then import the book into Calibre and clean it.
I then side load it into my Blackberry Playbook. (I don't use my Sony ereader because I need a brighter back lit screen).
Please ask if you require more help.