First, you will not lose any files. Actually, it is a little like the Format utility in Windows, the difference is that it formats only the free space on your hard drive.
Simply speaking, as you use your computer you are adding and deleting files. However, the deleted files are not really deleted, they are marked as "available for use" in the File Allocation Table; this allows other programmes to write fresh data over the old `deleted`data. So, anyone with a little knowledge can recover your "deleted" data.
Wipe Free Space checks your hard drive to find all the free space (some of whic