Spurred by the growth of Internet and related technologies, which have made the process of collecting the detailed information about customer easier, adding to the volume of data available to businesses, e-tails are beginning to deploy personalization in a large scale. This study first starts from a literature research on the adoption and use of CRM in the e-tails. Secondly, providing insights into internet-based customer services enabled with the help of IT implementations related to CRM, this study extends into a research on the influences of provision of extensive information - including personalization - on consumer``s choice of sites when visiting and purchasing online, and empirical research into consumers who prefer to purchase book online rather than offline, especially in online bookstores which have Korea-based operations. To do empirical research, with the modified framework which is originated from WebQual instrument, we make hypotheses focused on the price, provision of information about book, and personalized provision of information which all have been insisted on as characteristics of book, and then conduct questionnaire survey. As the results of research, we show that the consumers`` perception of and the influences by the accessibility of extensive information and personalized provision of information in online bookstores are significantly increasing, though they don``t come up to the effects expected by e-tails yet.