I didn't get a straight answer before, so I'm repeating my question. When enabling the "energy saver" feature that turns off your hard disks after a certain defined period of time, what exactly happens to your PC? If I have certain downloads going on the computer and this feature comes into effect, do these downloads stop as well?

"what exactly happens to your PC" It starts to treat the hard drive the way it treats a floppy drive. That is, when the hard drive needs to be accessed there is a delay while it gets spinning up to speed. If you have downloads occurring the hard drive will not go into energy saving mode at all, since it needs to be idle for 3 minutes in a row (or 5, or 10, whatever), before stopping. An active download will write to disk more often than every three minutes, so the hard drive stays spinning. But even if you had a long pause on a download such that the hard drive did stop, it would start up again as soon as windows wanted to use it.