1. "But when I look at the obvious programs they are 200Kb or less" I have no idea what this is supposed to mean.
2. You tell us what's filling up your hard drive, giving us info such as folder or file names, and we might be able to help identify their importance.
3. Did this all of a sudden happen?
4. Have you emptied temp folder, temp internet files folder, cookies, history, etc???
We'll need a lot more info than what you gave, none of us here are psychic.
Matt J.
Please always take the time to backup any and all data before performing any actions suggested for ANY problem, regardless of how minor a change it might seem. Also test the backup to make sure it is intact.