best book to learn positional play

I know there are a lot of books on middle game and  all but i was wonderig what everyone's thoughts were on which book or software or w/e was best for learning positional play?

I am making my recommendation on based on the fact that our ratings at this site are about the same.  A great great first book on Strategy is Simple Chess by Michael Stean.  It is cheap at Amazon.com   The writing is crystal clear and the examples are very illuminating.  I think a lot of the other books on Strategy are for later on in our development. 

I highly recommend Simple Chess by Michael Stean

i have gained a great deal of instruction from Lev Alburt's, Comprehensive Chess Course Series, and The Giants of Strategy by Neil McDonald (Everyman Chess). Jeremy Silman's books are very helpful for understanding imbalances in a chess position.