Information on Folding at Home click here
Not malware but a scientific research programme based at Stanford University in the USA.
It's looking at how proteins fold or misfold and has a bearing on some forms of cancer and diseases such as Alzheimers.
It runs as a background service releasing your cpu from folding as soon as another program wants to run.
It is taxing on your system as it will run the cpu flat out all the time (although it is adjustable for how much cpu usage it is allowed)
Also have a look on the Folding forums click here
and see click here