I am looking for a method to securely erase only part of a hard drive. I am selling my old Mac and I would like to leave the OS system as it is for the next owner (who I know). I will be able to look for and delete all files relating to me, so my question is, what is the best method or software (preferably freeware) for fully erasing file traces and data from the "empty" part of the hard drive? I have seen something called BOOT AND NUKE (www.dban.org) but it seems to be for erasing the whole drive (though I am not sure). Does anyone have any sage-like advice? I should point out that it is not an Intel Mac, therefore Boot and Nuke probably won't work.