Do I need to unresgister the old nook before setting up the new one? If so, do I download the books off the old one then unregister, then register the new one and sideload books to it? What order do I need to do this in?
If you register the new Nook to the same account (email address and same credit card) all the books and apps you have purchased from B&N should be available for download on the new device - there is no need to deregister the old unless you are planning to give it away or sell it. You should be able to copy sideloaded material to the new device.
Thank you for the information as well; my concern is also that I cannot find the ebooks i purchsed from my old nook in my account.. any thoughts on how to retrieve what was bought from my old nook to the replacement?
Are you sure you used the same email account when registering the new device
Occasionally the HD seems to have difficulty finding all of the books in the library. One of my wife's eBooks never showed up on her HD, but was in the library online and on the other devices and apps. I just sideloaded it and it works fine. Luckily for us, this has only happened the once. Generally, everything should show up unless it's not compatible with the device.
If nothing is showing up, make sure you registered your new device with the same email account.
I have had a situation in the past weather it was an e-book or game; when it was a compatibility issue. I wound up leaving the e-book on my other device.