In addition you the above you might also need to:
Here's the skinny if you (after downloading and installing V.3 or 2 and still not working, you have to delete the 'Digital Editions folders from your nook folders to officially 'unauthorize' your device. So incredibly confusing, but incredibly happy to have finally figured this out. HAPPY READING!!
1. Plug the NOOK on the computer using the USB cable.
2. Open “My Computer”.
3. Open the “NOOK” drive.
4. Delete folders named “Adobe Digital Editions” and “Digital Editions”.
5. Go back to “My Computer”.
6. Right click on NOOK drive and select Eject.
7. Unplug the NOOK from the computer.
8. Open “Adobe Digital Editions” application.
9. Plug the NOOK on the computer.
10. Pop-up window will be appearing saying “Device Setup Assistance”.
11. Select “Authorize Device” to authorize the NOOK.
12. You will see the NOOK folder under Bookshelves column.
13. Drag and drop the eBook on the NOOK folder.
14. Eject and unplug the NOOK.
15. Using the NOOK, go to “Library”.
16. Open your eBook and enjoy reading.