All the machines at home run Mac OS 8 or 9, and I don't see that changing anytime soon. One of the OS X sites I read keeps asking questions like "what application keeps you using Classic?" (where Classic refers to OS 9). I actually wrote back and replied that the 'application' which keeps me using OS 9 is OS X. Despite Steven Jobs' assertion that OS 9 is dead (for developers), OS X just ain't there yet. Not enough drivers for printers, scanners and such. Not an easy way to work between OS 9 and OS X boxes (since my 8500 can't run OS X, and it's not officially supported on my iBook). So anyway, the book is basically my way of keeping up with the future.
Getting back to the 'life in the universe' books... Rare Earth promotes the thesis that simple life, up to the level of bacteria, probably is ubiquitous, but complex life, eukaryotes, animals, are so rare that Earth is likely their only home. It is a somewhat long book, replete with citations, arguments and theorizing. Considering that the topic is largely full of unknowns, the book is of course all speculation, but the authors argue in the manner of a debating team in high school, seemingly believing that if they pile enough 'ifs' on top of each other, they will win the debate.
Life Everywhere is more clearly identified as speculation, though the author does seem to believe complex life will be found off Earth eventually. One chapter is even devoted to Rare Earth, taking the authors to task for their assertions in such a speculative field. Overall this is a lighter book, which was alternately more satisfying (since it made no claims to certainty), and more disappointing (since Rare Earth, whatever it's faults, was filled with detail and citations).
Next up in the reading queue besides Missing Manual is Breaking Windows, subtitled 'How Bill Gates Fumbled the Future of Microsoft'. Should be mildly interesting...