Hi I'm taking my external HD back to Apple tomorrow so I need some help wiping it in a way that data cannot be recovered by somebody else. I know the chances of Apple going through it are probably zero but I want to do it just in case because I have some really sensitive information on here. So basically, if I perform an ordinary format using Disc Utility, surely the data can easily be recovered? So what should I use? Any good software out there that will do that? Any tips and suggestions welcomed! Thanks in advance!