A related question you did not ask is "What format is best for FBReader?". I started using Plucker, but have recently switched to MobiPocket which I still think is best for FBReader on a 800x480 screen. An alternative is .LIT exploded to .OEBZIP, which is good for "secure" e-books, and generally gives larger images than MobiPocket (which can be a disadvantage on the 770 if the images are too large for the screen).