I have a 70.1 GB hard drive, but since I used System Restore that has gradually went down, over a period of a week, to the point where I only have 665MB left free. This is a problem as you can no doubt imagine, as this space is not being used by programs or by anything that I can actually use.
How do I undo the space that has been taken up? I tried undoing the System Restore, but the hard drive space was still taken up as it was previously.