Exactly the same thing happened in my school; they were getting rid of their old computers from a couple of IT labs.
I proposed to create a BOINC Farm in the name of the school, and lead it as a side project until I leave the school, when other people will take over.
Sparing you of the administrative details, I currently have 23 computer at my disposal (Dell Optiplex 390, i3 2120, 2GB RAM), and they are all hooked up to a network switch, running 24/7 at Rosetta@Home.
So to answer your question, distributed computing through BOINC or the World Community Grid? I learned qoite a lot through this project, and be ware of the electricity cost, but if that isn't an issue, you might have fun doing it. I also managed to scavange the PCs for some 500GB WD Green HDDs, and replaced them with some 60 GB HDDs. I now use the WD Greens for my home storage server.