What OS was this? Processes like these (Folding, Seti, etc) should be "niced" on *nix-like OSes to have the lowest possible priority. Not sure what this looks like on Windows, but I imagine it's possible.
In windows, each process has one of 6 priority levels, and each thread has one of 7 priority levels. The combination is looked up in a table and yields one of 22 values between 1 and 31. http://msdn.microsoft.com/en-us/library/windows/desktop/ms68... You can manually change priority levels by right-clicking a process in the Task Manager. Not sure how to do it automatically or on a command line.
nice doesn't help with I/O pressure or memory contention, particularly if it used enough memory to contribute to swap activity. Even something like pressure on the system L2/L3 caches can be a big deal, particularly on older systems where those were less generous.
Agreed, although I would note that at least on Linux and FreeBSD those haven't been a realistic option for a terribly long period of time – if the user didn't go to school recently, it's likely that they weren't an option.
(also, not sure about cgroups but ionice did absolutely nothing useful with swap churn when I tested it awhile back)
