REQUIREMENTS
Equipment
To run EVO properly, your PC should fulfill certain minimum hardware requirements, especially if you intend to send/receive video/audio with good quality and interactivity:
A computer (not older than 4 years if possible): Windows (XP, Vista or 7), Mac OS X (10.4, 10.5 or 10.6) or Linux (distribution not older than 2 years).
A connected headphone to your computer. That’s a minimum. We recommend using USB headset or echo canceling microphone (see our hardware recommendations).
A microphone (built-in or not) if you want to speak. Only if you don’t have a headset.
[optional] A web cam (built-in, USB or HD connected to a video grabbing card)
Software

Go to the Java website at http://java.com
Click on Verify installation to make sure that java is installed or to get the newest version of Java
If you don’t have it or want the newest version (recommended), click on Download to get it
Connection
A good Internet connection (1 Mbs download and 256 Kbs upload at least)
You have to make sure that some ports are open and not blocked by local firewall (details).