Just wanted to put in my two cents:
Ansileran, if you're able to read ePub files on your PRS-505, then you already have the most up to date version of the firmware. If not, you can download it here:
http://esupport.sony.com/US/p/model-...d#/downloadTab
Also, on using
Calibre generated files (ePubs vs LRFs), in my experience I've found that the ePubs are very usable and the conversion functionality is great within Calibre. With LRFs however, Calibre stopped development on that functionality a while ago, and there are few LRFs created from Calibre that did not crash my 505 at some point or another. So I would strongly recommend that you convert to ePub (and update your firmware if you haven't already - the updated firmware also supports the reflowing of PDFs, which is of great utility).