Whether getting rid of an old computer or just making a clean start for your favorite hard drive--do hard drives even get to be honored as "favorites?"--it's important to wipe it clean. With one's and zero's and data recovery, though, it's harder than you might think to make sure that your personal data is gone forever. This collection of drive bombs showcases four free programs for internal and external drive data deletion, as well as files and folders on the fly.

Eraser shreds files on-demand or by schedule. (Credit: Heidi Computing)

For shredding individual files or folders, or entire drives, Eraser reminds me of an ugly, but effective hit man. Also known as Heidi Eraser, after its publisher, the program's interface is plain and unadorned, but also easy enough to figure out and because of its simplicity will work with operating systems as old as Windows 95.

Mouse-over tooltips help identify tasks that the generic icons take you to, and a native Windows Explorer context menu addition makes one-shot shredding easy despite the lack of a simple deletion button in the main interface. Otherwise, when deleting files both large and small, you'll need to first add the file or folder to the spreadsheet display. Drives can be added to the shred list in the same way. Users can schedule shreddings, too--handy for routinely wiping free disk space. Four secure government-sanctioned deletion algorithms keep those deletions dead, including algorithms from the U.S. Department of Defense, the default Gutmann method, Pseudorandom Data, and DBAN for hard drives.

That brings us to DBAN (Darik's Boot and Nuke), which wipes internal hard drives only. It comes in two flavors of data-destroying pain: one to be installed on CD or DVD, and one for floppies or USB thumbdrives. Once you have the program installed on the proper removable media, you need to make sure that your computer will boot from that drive. If it needs adjustment, this can be done from your BIOS. The Autonuke option will delete all detectable hard drives, including the C: drive. The interactive mode lets you choose which hard drive or partitions you'd like to obliterate. Once you've chosen what you'd like to destroy, F10 will start the process.

Darik's Boot and Nuke warning screen. (Credit: Darik Horn)

DBAN's not for the timid. Since it runs separate from the operating system, the user interface is basic and similar to what your BIOS looks like.

File Shredder's also seen some good notices. Covered in a drastically more modern interface than Eraser, File Shredder looks like a file deletion-specific version of Windows Explorer. It supports shredding files both individually and as a group, aided by simple commands such as Add File and Add Folder. Once you've chosen your targets, you can choose from five shredding algorithms, ranging from simple one pass to the Department of Defense 5220-22.M to the Gutmann algorithm. The Disk Wiper mode can clean free space on a hard drive.

Despite its modernity, File Shredder lacks a scheduler and offers no hooks into the recycle bin, which means that files that are already there must be dealt with by hand before they can be shredded. Unlike Eraser, it doesn't do full drives, either.

CCleaner also contains a hidden shredding component. Go to Options, then Settings, and choose Secure File Deletion at the bottom of the window. From there, you can adjust the number of overwrites the program will make on deleted files, from the standard one pass up through the Gutmann 35 passes. Also included are the three-pass Department of Defense standards and the National Security Agency 7-pass standard. CCleaner is probably the most user-friendly of the options in this collection, but it's really only for shredding files that get detected by the program. For more selective shredding, the other options are recommended.

Unknown to many, CCleaner contains a file-shredding option. (Credit: Screenshot by Seth Rosenblatt/CNET)

I'm including Zilla Data Nuker more as a warning than an actual recommendation. You should only use Zilla Data Nuker if it's version 2 or earlier. Version 3 installs the Relevant Knowledge spyware and doesn't give you the choice of opting out. However, older versions don't, and so they can stay on the table even though they don't include this horrible business practice.

As a program, Zilla Data Nuker works well, with multiple algorithms and a good-looking interface. Included are a scheduler and the capability to shred via context menu and to shred an entire drive. If it wasn't for the lack of the Gutmann algorithm and the business practices that the publisher now endorses, I'd recommend Zilla more strongly. As it is, give it a pass unless you have no other option.

With all of these programs, I found that file or drive size was a more restrictive determinant on shredding speed than anything else. These are definitely programs for users with patience: if you're truly concerned with sweeping away your data footprints, you probably shouldn't be too worried about how long it takes to wipe out any trace that you were there.

There are probably at least a dozen decent shredders out there. If you have a favorite that I missed, let me know in the comments.