There are a number of options for cleansing the drives of unwanted computers, from special wiping software to destruction services to manufacturers’ recycling programs. But what many PC owners don’t realize, experts say, is that these methods are often not enough. Two weeks ago, the National Association for Information Destruction announced that it could not endorse the use of wiping applications alone for deleting data from hard drives. Bob Johnson, executive director at NAID, said the data-destruction industry group would like to be able to recommend the tools, but that tests had left reason to doubt the wiping products…