Usually O Reily has good books but a little too high level...(Most of the publishers who sell books to colleges are junk and too expensive like Mc Graw Hills etc..)
(Are you in USA?) if so...
go to Barns and Nobels or even half price books (they have good choices) but before buying (any book) lookup some thing in them. If the thing you look for exists in the index then you're OK so far, if the thing you're looking for (for instance "configuring the keyboard", is there but tells you to "contact your system administrator" then trash the stupid thing! the whole book is probably a waste of money.
I remember looking for a Sun Solaris book and out of 10 I found, only 1 was worth buying! So be careful. take a subject before you shop and look it up, if you are satisfied with the answer the book gives you, then buy it.
Nothing's absolute, but this has been common experience with me.