[RAH]

If all the books are on Calibre, they must be non-DRM. Therefore, you are free to move them around as you wish. Sooooo, she could just hook up the Nook to her computer and using Windows Explorer, copy every thing in the Nook (it shows up as a separate drive, like an external harddrive) to her C: harddrive. Then do the restore on the Nook, register it for herself, and copy the books back to the Nook, into My Documents.

I am not sure about the memory card and how it interacts with the Nook, but again, if these are non-DRM books, they are just files. So you could put the memory card in a card reader and copy everything off it to a harddrive.

Another option is for you to just copy all the books from your Calibre library onto say a flashdrive or CD and give that to her. Then she resets the Nook and copies all the files onto it.