Harrington on Hold'em Vol 1 is a great instructional guide. It gives you homework at the end of each section, asking you to use what you learned in order to make the best play. One thing that is nice about the problem solving, is that the correct play doesn't always win the hand. He is very good about explaining why you made the right play, even though you lost the hand.
Theory of Poker is a good book, but I have a feeling you'd be better of with Harrington. Also, Harrington covers a lot of concepts that are covered in TOP.