Computer Facing Excessive Hard Drive Activity?

Recently, within the past few weeks, I've noticed that my hard drive has been running more than usual. I can hear it running, and I see the activity light flashing when the computer is basically at idle and not doing anything. The weird thing is that if I hit CTRL-ALT-DEL and bring up the performance tab, on the top portion of the graph, there is a spike in CPU activity, with the time interval being almost exactly every 60 seconds for about 2 or 3 seconds, along with corresponding hard drive activity. Then it stops and the activity spike repeats about 60 seconds later, over and over.