The objective of this study was to identify and analyze the two contradicted effects of the habits in a current used system on the acceptance of a new system. The first one is lock-in to a current used system, which negatively influence the intention of using a new system. The second one is familiarity and expertise for a new system from rich experiences through the repetitive use of similar system, which positively influence two relationships in the acceptance of a new system: usefulness – intention and ease-of-use – intention. For the validation of the hypotheses, 208 university students in Korea, who have enough experiences of word processors, were surveyed for the acceptance of Google Docs. The analysis of data from the survey showed all the hypotheses were supported with relatively low significance level.