Dawn, definitely go to
amazon, which is the exclusive seller of kindles, and also kindleboards(dot)com for more that what I can tell you

.
The basics: Kindle 1 came out a few years ago and was replaced by Kindle 2 which came out earlier this year (that's what most of us have). Kindle DX is much larger, and came out this summer. It seems to be used primarily by people who need a larger screen, some college students, and those who read a lot of text with pictures (IMHO it's not very "portable" compared to K2 just due to its size).
When you purchase a book, it's downloaded to your Kindle in a matter of seconds. You can leave it on your Kindle or you can delete it, knowing that it will remain in your Amazon "space". Some Kindle users like to store lots on their Kindle, others like to leave most of it in their Amazon account.
While it does have a text to voice feature, it is a computerized version (like the time/temperature person

) not "read" like an audiobook would be. It's adequate (my sp.ed. students like to listen), but obviously not read with any "personality".
Terri