Books on SEO?

Hi all,

these three books all have good reviews - I just don't want to buy three books on the same topic. Any opinions?
Search Engine Optimization: An Hour a Day - Jennifer Grappone
Get into Bed with Google: Top Ranking Search Optimisation Techniques - Jon Smith;
Get to the Top on Google: Tips and Techniques to Get Your Site to the Top of Google and Stay There - David Viney;

Cheers,
Don