Video Conferencing

I have been asked by a friend to look into setting up video conferencing for her company. She needs to connect up to five managers at once from different sites within one country (Ireland)over 128k internet connection. Bandwidth ( I think ) should not be a major issue as the video side does not need to stream terribly fast, just maintain a presence. A whiteboard would be a handy feature, also the ability to view .ppt files simultaneously.
Even if nobody can offer any advice on what’s required,if anyone looked into this before and gave up on the grounds of cost, I’d be interested to hear at what cost point (per site) did you decide it was unfeasible.
Thanks in advance.