From Kevin Solway:
Clean Disk Security gives you secure file deletion, making sure that deleted files cannot be undeleted again. Deleting a file normally just removes the file's directory entry, but the data itself remains on the disk. This program completely eliminates the contents of deleted files. The highly acclaimed Gutmann disk cleaning method is now available as an option. This program can also clean the Window's swap file, and can optionally clean unneeded temporary files from your hard disk, such as your Internet browser cache, files in your system's Recycle Bin, and can clear the "recent files" list. Comes with a direct disk viewer for discovering exactly what is on your hard disk.