how do I erase a hard drives info, I got some sensitive work related data on the hard drive, I would like to completely erase it as it is still under warrenty, it shows up when I hook it up, but only under like sometimes 4gbs (in the bios screen) just like random numbers, and random as **** drives. If possible I also got a lot of music converted to mp3 on there, I would like to get that off to.