This set of posts comes from Pastor Mark Driscoll and his wife Grace. The sermon series The Peasant Princess brought up dozens of questions that they felt they should respond to. The result is this blog series: Christian Sex: Frank Answers to Honest Questions.
Answer: No. Genesis 12:10–14 says that Sarai was beautiful, even in her old age. Some women are lovely and to recognize this fact is, in itself, not a sin. However, recognizing a woman’s beauty does become a sin when a man lingers and lusts after that beautiful woman and begins to undress her or connect with her in his mind.