There is a workaround for the e-books thing, which I do routinely, as I hate being restricted to one company's ecosystem... remove the DRM from any books you buy. I buy books from Amazon, B&N, Sony store using their various apps on my PC. I then strip off the DRM using very simple Python scripts available freely on the internet (google "remove DRM from Kindle epub" for example) and use Calibre to convert them all into epubs if they are not already. I can then load them onto my reader of choice, which is currently a Sony, and read them.
You should be able to do exactly the same, and load them onto your NC, and read them with Aldiko, Moon+ or your ebook reader of choice. There is some loss of pure convenience but it is not serious - it takes me about 2-3 mins from download on PC to reading on ereader, and de-drm, import to calibre, conversion, and upload to ebook are all batch processes so it really takes very little time. And it means that you can buy books not just from B&N but ANY online store (better availability, better price) and read them in the format and on the device that YOU want to. You'll also never be held hostage to the seller going bust, changing formats, etc, and can share your books with your mum like you would a normal book.
There is a bit of a learning curve to the above, but its well worth the effort (and its less technical than getting your Nook in good shape!