This paper describes a high school project where the mathematics teaching and learning software M@th Desktop (MD) based on the Computer Algebra System Mathematica was used for symbolical and numerical calculations and for visualisation. The mathematics teaching and learning software M@th Desktop 2.0 (MD) contains the modules Basics including tools for teachers and students and fitting routines, Differentiation, Integration and MDTools. The homepage of the project is www.deltasoft.at. MD's engine is Mathematica. An evaluation copy of MD is downloadable. After a short introduction delineating the initial situation, the aims of the project, and the methodological frame, we describe the teaching process and final outcomes. First results indicate that computer-based teaching intensifies the students' activities, their level of attention, and their contentment with mathematics. (Contains 3 figures.)