Congratations on your new 505! It's aa great machine! I agree with kelly, I get a ton of books from my local library. I have never been much of a book buyer; I have always been an avid library user. The 505 is perfect for getting library books. Search for your library on this site :
http://search.overdrive.com/ and you can go from there.
There are also a lot of free books on this site- check out the links to the free books for the format you want (epub is my favorite).
welcome!