The notion of electronic commerce (E-commerce) has been gaining in popularity with the rise of commercial activities on electronic networks, especially on the Internet. In the academic world (e.g. Brynjolfson & Smith [1999], Shapiro & Varian [1999]) as well as in governmental organizations (e.g. OCDE [1996-19998], Lorentz [1998], US Dept. Of Commerce [1998, 1999]), many optimistic analyses see the Internet as a way to completely re-engineer the relationship between the producer (good manufacturers and

service providers) and the final consumer, leading to major productivity progress in transactional activities. This is essential since those activities became dominant in

developed countries during the twentieth century (Porat [1977], Wallis & North [1986], Jonscher [1994]), and they were characterized by very slow progress in productivity.