Another vote for the Kindle 2. As already mentioned, the Kindle doesn't need an extra application to load books -- just go to the store, click and you're done. There is a bit of a downside (namely, you're all but locked into buying e-books from Amazon) but for someone who is not technically inclined, a) it's worth the ease of use and b) it may not be a big issue.
You might also want to load up the new K2 with a bunch of public domain books as well, save her from buying all those Jane Austen books.