As AprilHare and Grooks said--you should be able to read both. But, it probably suffers from the same problems as the 505--you can only have one type loaded at once. For some reason, if you have an ePub loaded, PDF's won't work and vice versa. It's my understanding that this is an Overdrive problem--not a Sony one. Also, although both ePubs and PDFs work, ePubs work a lot better. Most of the PDFs I've downloaded are too small unless reflowed--and if you reflow them weird paragraph/page breaks can occur. Something I'd be upset with if I had purchased the books--but I'm willing to put up with for library downloads!
dordale
