bructer, skype is ok but it has a limit of 5 users conferencing at once. A better program that I use all the time is Ventrilo. Download the client here : http://www.ventrilo.com/ Afterwards we can all connect to a public Ventrilo server ... unless one of us have a private Ventrilo server.
I will let cgm1402 decide on all of this because he is the one organising the conference call.
conference call: Skype offers conference call capabilities and its free between Skype members. Ebay bought skype and it works well. Its free and easy to install and use. It would be a good way for the group to have voice communication at no additional expense.