If you have the latest firmware, it supports DRMed (encrypted) ebooks in Adobe formats. See the
Books on Board EZ Reader help page for how to authorize your device to your AdobeID. The EZ Readers are Hanlins, just like the BeBooks.
Adobe ePub is the most popular ebook format in Europe, and BoB is a good US site for buying ePubs (you may need to spoof the site to buy US ebooks from outside the US).
Other good formats for DRM-free ebooks on the Hanlins are FB2 and MOBI. Calibre (has its own forum here) can convert almost any DRM-free ebook into your favourite format.