Originally Posted by 4nefertiti
Using the internal PRS900 memory is much faster. However, if you want to make sure everything is backed up, a memory card is the way to go [yes I realize that the books are backed up in the reader or adobe library (or calibre)]. I had my previous reader crash while I was traveling. Since my books were on the sdhc card, I removed it, sent the reader to Sony, and inserted the sd card on my kids reader and I picked up right where I left off in my book.
I have all my books backed up in my Calibre library, which I back up on a DVD periodically and also online. I would never keep the only copy in my reader, either on internal memory or an SD card, because if you lose the reader (or it gets stolen) you've now lost all your books as well.