I recently purchased "Modern Chess Strategy" by Ludek Pachman, but the descriptive notation makes the content a bit confusing. A book that uses the algebraic notation would be better.

How to Reassess Your Chess - It made my rating go from 1770 to 1856 in one week, and it's definitely worth every penny. Buy the new edition, as it has excellent examples.

How to Reassess Your Chess, Chess Strategy for Club Players, Simple Chess, Secrets of Endgame Chess Strategy and How To Play Chess Endgame by Muller, are all appropritae for your level, they are all good books.

Which chess book would benefit a guy with 1500 ELO the most?

Thanks!