OK, it might be a good idea to give everyone who is new to ebooks a few pointers.

Useful links:

http://www.gutenberg.org/ free public domain ebooks
http://www.teleread.org/blog/ everything ebook related

Now FBreader is great for reading plain ascii, html & some xml formats (like fb2),
but is unable to read any of the DRM'ed formats such as *.lit etc.
And last but not least it cannot read PDF (which by the way is a horrible
format for ebooks, fixed page width, height, font, page no. etc)

I myself am quite happy with the way fb2 renders content on the 770,
It doesn't offer all the features I used to enjoy on my Hiebook, but 225 dpi & proper backlit screen makes more than up for that.

Hope this helps...