Hard Drive Cleaners

[scotstone]

When using hard drive cleaners such as Killdisk, Eraser etc, to remove confidential data, will it be necessary to reinstall the operating system and antivirus programs or does the cleaner confine itself to unused space on the hard drive?

[Huderon]

Eraser has an option to clear all unused space on a drive, but if there is a lot of free space it can take quite a while to do it - best done as an overnight task I'd suggest.

[fo3nix]

Also note that they're not foolproof.

Probably enough for the average Joe not to be able to recover stuff, but perhaps not good enough to stop a government.

You can also just erase certain files at a time.