Originally Posted by Rizla
Use the ebook reader that comes with Calibre. It's called in ebook-viewer.exe and it's in the calibre program folder. I think it will open most formats.
Be aware that it modifies the actual epub file - file sizes change - keeps a note of where you are etc... not vitally important unless totally OCD about files being absolutely perfect but something to note...
Otherwise pretty good reader, easy to use and handles a multitude of formats...