I think desertgrandma did a great job summarizing the most important points to the Kindle and Sony in just a few sentences!
If you are into library books, check out this link and search for the types of books you want, or your local library to see if it has ebooks
http://search.overdrive.com/ If you find there are a lot, and this is a good option for you, you might want to check out a sony in a little more detail. Amazon has new releases for less expensive for Kindle is you prefer to buy *some* books. check out the "which one should I buy" forum and read the posts there to help you get a good start on which ereader might be best for you!
And Welcome!