I have tried TeamSpeak, Vetrillo and ImVox. And for being free I like ImVox alot. It is very easy to use and access. Granted I have only had 4 people on at one time but it ran while gamin on an older comp with no problems.
I am trying to do the same, where do you register for the stress test? I have looked on the forums for where to do it and can't find it. Although it is probably right in front of me.
Scratch that, I was right. It was right in front of me, lol.