Agreed - forget about the 600
The 350 is slightly smaller (5" vs. 6"), with a tradeoff that, as I understand it, the screen resolution is slightly better; some say that means that one can read a smaller font better, making a dent in the "smaller means more page turns" assertion. I've not read on a 350, so I don't know firsthand.
Main difference between the units: the 650 has audio capability (mp3 and AAC files), as well as slots for a proprietary Sony storage card and an SD card (regular, not micro). And ... the 650 has a sturdier stylus!
