I have had my computer for about three years and have had no noises from the hard drive until recently. When my son plays certain games it sounds like a fan going on quite loudly and constantly. Have got him to exit the game as not sure if it is dangerous or not. As soon as he gets out of a certain part of the game it will stop. Has only happened two or three times but do not know if it needs looking at or not.
It sounds like your drive is going to fail. I would backup all data from this drive in case it does stop. You could run CHKDSK from the Command prompt. This will check for bad sectors and try to fix them. You will have to do this from a boot disk before windows starts.