Good to have your new company, DP. You may be snookered, though, because many ebooks are padlocked with DRM (Digital Rights Management) znd can't be easily transferred from one device to another.
It's a bloody sin, I know, but we can't discuss here how to strip DRM because the process -- no matter how justified -- is illegal (instructions all over the net, though).
I'd strongly advise you to download the free (or by voluntary donation) Calibre Library Software (
http://www.calibre-ebook.com). It's the best there is. And you'll find the magnificent Sony hardware (with its notoriously weak library software) and Calibre a marriage made in heaven.
Of course, it would be better for quick and more expert advice to post about your problem in the Sony-dedicated sub forum here.
Good luck and best wishes. Neil