overwriting the hard drives 3 times?
Doing it once is sufficient. Drive erase/wipe is built into several backup utilities.
Think of it this way, have you ever been able to recover even one document that was truely overwritten (not just updated, but the disk block was overwritten)? If that was so, you could always recover older information on a hard drive. The last time you could even remotely see what bits may have been written were from old double sided 5 1/4 floppy disks that were exchanged betweeen double density and high density drives where the read width was half the width of the double sided drives. This only made the data unreadable with parity errors unless it was read in the last drive that wrote the information and that was usually a cr@p shoot. Most of this is paranoia and urban legend material. Makes for a mediocre scifi flick, but try and recover anything from a erased/wiped disk, you won't be able to...
