A posting to the listserve goes to all students in the class. It is similar to holding a discussion in a traditional class with the advantage that you will have an opportunity to respond to every question or comment if you so choose or ask a question of anyone in the class. You always have an opportunity to participate in a discussion. No special software is required to access the listserve other than your e-mail program. For the most part, bigger and faster is better.
Requirements change quickly as the Web changes.
Only a couple of years ago a Pentium II with a 100MHz or a 133MHz processor was a fast computer. Now they are barely able to navigate the Web. 128MB or more is even better. The third measure of speed would be your modem speed and type of Internet connection. A 14.4 modem is too slow.