Has anyone heard of Skype? http://skype.com/ Its like those call over the internet programs that were rampant a few years ago, but that eventually you had to pay for.

Downloading is free and installation is a breeze!

This was created by the creaters of Kazaa so presumably it'll stay free... (we can hope!) The quality is excellent, and all you need is a mic and your friends id - check it out if you haven't already:)