I just read a great book.
"In the begining ... was the command line" by Neal Stephenson is a great history of operating systems written in a somehwat non-technical manner. I'd say this is a must read for anyone who uses a computer on a regular basis.
In the spirit of things being free, the full text of it is online in many places including the site below:
<a href="http://www.cyberpunkproject.org/lib/in_the_beginning_was_the_command_line/">http://www.cyberpunkproject.org/lib/in_the_beginning_was_the_command_line/</a>
I've read one other book by the same author, Snow Crash, and after this one I certainly intend to read more.