http://www.vidarholen.net/~vidar/overwriting_hard_drive_data...

"The purpose of this paper was a categorical settlement to the controversy surrounding the misconceptions involving the belief that data can be recovered following a wipe procedure. This study has demonstrated that correctly wiped data cannot reasonably be retrieved even if it is of a small size or found only over small parts of the hard drive. Not even with the use of a MFM or other known methods. The belief that a tool can be developed to retrieve gigabytes or terabytes of information from a wiped drive is in error."