Since I have been living in Mexico and the kids are scattered I have been using Skype (after playing with Vonage for a while). I works great and we have started using it for work also. It supports video and there is a program (beta) where you can share desktops, similar to the old Webmeeting. Computer to computer is free and calling to land lines like 2 cents a minute-you buy time on line for the land line calls.
Once in a while you get an echo or a dropped call but this has been very infrequent over the past year.
It is excellent as far as I am concerned and if you have a newer Apple with the camera and mike built in you don't need the headset.