I've seen it, but I don't know about listening for radio signals. I will say its better to do something proactive than to sit on our hands and wait.
I don't SETI anymore, multiple reasons, but to answer your q about getting more out of SETI, it will use all available resources on a secondary basis. what I mean is that if no other program is running, it will use all it can, until something needs resources, then it gives them up. if you screen saver is set to off, and you don't have a bunch of background programs running, then you are probably getting all you can out of it.