Hi CarolD, welcome to MR!
I've had a Kindle now for over a year and I really don't know how I got along without it!!
The Sony devices are really good too from what I've read (around here). If I were buying a new device now, I'd seriously consider the 300 or the 600. I like the size and clarity of the 300, but I'd really miss having a dictionary. The way you use the dictionary on my K1 is really clunky; I tried out a 600 and it's sweet to be able to double-tap the word and get the definition right there!
Anyway, Sony experts will probably be along shortly to answer your technical questions. If not, try another post in one of the Sony forums.