I found the Reassess Your Chess Workbook the best chessbook I ever bought. Its the only book that taught me anything that I could actually use to help find moves at the board - with the exception of some opening systems I learned from Romans Lab DVD's. The ideas about imbalances and how to use them is fundamental to planning moves.
Jeremy Silman's books

The Amateur's mind is a definite first. Understanding WHY you are making a particular move is what I got out of it.

I think Silman's Endgame manual is his most important for early players who want to master chess, but I hear the workbook is great--can you buy a non paper version for your laptop?

I think Silman's Endgame manual is his most important for early players who want to master chess, but I hear the workbook is great--can you buy a non paper version for your laptop?
Why not work on both, Silman's Endgame book and Amateur's Mind? Both are useful and it'd break up the study in a good way.
I have Amatuer's Mind, very helpful, and his Endgame manual, which is also very helpful. However, if you're not a C rated player or higher, you only use a small portion of the book, and you can get pretty much all the info from Amatuer's Mind coupled with his "Complete Book of Chess Strategy". I was going to get the Reassess books, but waiting until the 4th edition comes out.
Which one is better to improve your chess?..
The Amateur's Mind or Reassess Your Chess Workbook
I want to buy one of them but I don't know which one...