Small Stakes Hold 'em: Winning Big With Expert Play by Ed Miller and David Sklansky is likely the best book for learning and becoming a long term winning limit Texas hold 'em poker player.
Miller is the primary author of the text and is known as the "noted poker authority". He has live as well as online experience and has a deep understanding of the game. The book is intended for use in small stakes full ring limit games, the type you usually find in most casinos, but the concepts also apply to shorthanded and online games as well.
Limit poker is very mathematical in nature, and Miller breaks down a winning strategy from preflop hand selection to betting postflop, aggression, and pot odds. The book has plenty of examples and hand quizzes, and the preflop hand charts are superb. Though the title says "small stakes" it will easily help you crush live 10/20, 20/40, or possibly higher games at a casino.
Miller also has some instructional DVDs which are quite good, but this book is definitely a must own for anyone who is a beginner or intermediate limit hold 'em player. For more advanced concepts, Sklansky & Malmuth's Hold 'em Poker for Advanced Players is probably best, but this is still worth a read.