This paper is an evaluative report of forty Grade Seven students using a CALL courseware on enhancing learning English, in comparison with a control group of the same size with traditional pedagogy (non-IT) within two weeks. Unlike previous CALL research done on their students' learning attitude or oral ability in Hong Kong, the research focused on testifying the benefits of CALL to junior secondary students' learning English usage through a linguistic post-test, and depicting their perceptions of its user-interface design and instructional activities through a semi-structured survey. Research findings confirmed that in each academic ability group, mean post-test scores were higher when using CALL than not, and that median-ability students had the best post-test performance, compared with other ability groups. Survey responses helped improve the user-interface design with an attention to academic ability factor for future instructional activities.