This paper deals with the development and evaluation of a system for a one-on-one digital English classroom by integrating speech technologies. The system is designed for English oral practice and assessment for students using their handheld devices (PDAs) with wireless connected environment in a classroom. The system consists of four modules - speech, testing, learning portfolio, and teacher management modules. An evaluation study was conducted to examine how students used the system by analyzing the system log data, questionnaires, and interview. The results showed that (1) students increased their performance on oral practice (the number of times of 'wrong answer' and 'answering a question' decreased); (2) students increased their confidence in speaking English; (3) students highly accepted the learning style of using handheld devices for English learning; and (4) functions for providing students' statistic data to the teacher was very useful.