I am a mid-30's Australian computer scientist who has been working in (non-computer) administration and policy jobs for most of my working life. I rip-apart PCs in my spare time and try and put them back together again. I joined up to SETI back in 1999 as I too could see the potential processing power going to waste on idle PCs.
Thoughts about SETI and SETI@home
I'm really not convinced one way or the other on whether we will ever be in contact with ET life...the argument that the universe is so big that other life has to exist in the right place and the right time does sway me towards doubting it...but I do find it hard to believe that Earth is the only place where life exists / has existed / will exist.
SETI@home is a fascinating idea and I think it has gone well past the experimental stage. The ability to maximise available processing power may have far-reaching consequences. Whether the project finds ET life or not doesn't really worry me. I will be interested in seeing where distributed processing ends up being used.
As a small example: install sensors/processors in every light-pole by the roads - as it gets dark it turns the lights on. Since you have a processor, why not get the sensor to also detect rain or fog and send a message to the nearest "alert" sign of the rain/fog to warn oncoming cars. If it gets cheap enough, add wind direction/speed and air pressure and humidity sensors. Now, lights across the country can help report the weather...when not reporting, use the spare processing capacity to do micro-forecasts of the weather.
If the light poles can sense the traffic conditions and communicate to cars, as you near an intersection, your car (knowing where your destination is) could select the best (shortest dist, shortest time, least gear changes) route and update it in real time. The cars themselves can warn poles ahead of them that they are coming thus helping in forecasting traffic conditions.
Not very SETI-related example, but that's where computers are taking us. Any spare processing capacity in the light poles and cars could then be devoted to other luxuries like SETI or analysing the share market or whatever.