have you thought about picking up a used prs-500, you'd save a pile of dough and have a dedicated reader
I'm much happier with mine then with a laptop(converted an old school powerbook to a dedicated ebook reader)
the screen just doesn't work for long reading IMO.
I found a dark background with light text worked best for me, and a fairly rounded font(I think I used the one recommended as being easiest for reading on the sony on the laptop also)