We've had great luck using EVO in our research group, and I've helped set up "videoconferencing" computers in a few rooms on campus. Take a relatively modern computer with a video card (we've been using nVidia GeForce 9500 GT cards, or something comparable), connect a webcam and a projector, buy a decent echo-canceling microphone/speaker (we've had good luck with Phoenix Audio Quattro2 devices (www.phnxaudio.com)) and you can have a decent videoconferencing setup for not too much money.
EVO also has support for connecting to SIP and H.323 systems, so you can use your EVO setup as a plain H.323 client or allow H.323 users (Polycom systems or whatever) to join your EVO meeting. And all meetings include telephone bridge access so users who have old computers, no microphones, or microphones that cause echo can join the meeting, too. You can also record all the audio and video streams to your hard drive and play the entire meeting back later. All for free.
The EVO website suffers from a bit of poor English, and the user interface is a bit to "happy" for me (lots of colorful icons all over the place), but if you can overlook that, it really is a great system that's been working remarkably well for us.
