I use dropbox on my eink readers. Just install it on your pc then use the browser on your ereader and go to
www.dropbox.com/m to access your files. Just login and all of your files are there. My calibre library is in my dropbox folder and that is wonderful easy access to all of my books. Any eink reader with a browser can use this. As long as the Nook ST has a browser you are good to go.
Quick and easy.