Why doesn't your mom just go with an mp3 player if she prefers to read pBooks?
I finally got to play with a 505 at my local Target. It is sleek and small and I liked the screen contrast (it seems a bit brighter than my Kindle). That said, those little buttons on the right side did not work for me. The round buttons were a bit better. It took about 5 mins. or so to figure out what was what so I could maneuver around. About the same amount of time it took me to figure out my Kindle.
I like my Kindle being bigger. It's just more comfortable for me to hold than the Sony. And my original reason for buying is still valid (content and pricing) and I'd buy the Kindle again.
It is great that there is so much choice in readers, even if choosing can make one go insane.