This paper presents a research proposal on user-oriented evaluation method to compare the usability of Internet search tools. Cognitive style and problem solving style are identified individual difference factors. Meta-search, portal and individual search engines are Internet search tool available. Usability of each search tools based on relevancy and satisfaction is another factor of this study. The ultimate aim of the research is to contribute to the knowledge concerning individual differences and information retrieval technology. In particular we hope to get a better understanding of which presentation structures and user interface attributes work best and why.