Do you want to completely wipe your hard drive including removing the operating system and leave it blank?
If that is what you want to do use the following link to download an ap that will do it:
Active@ Kill Disk - Hard Drive Eraser 1.1http://www.download.com/Active-Kill-Disk-H...tml?tag=lst-0-4
Active@ KillDisk is powerful and compact DOS software that allows you to destroy all data on hard and floppy drives completely, excluding any possibility of future recovery of deleted files and folders. This is security software for unrecoverable data elimination for any computer capable of booting in DOS mode from floppy drive. It uses access to the drive?s data on a physical level via BIOS bypassing logical drive structure organization, thus it does not matter operating systems and file systems located on the machine, it can be DOS, Windows 95 / 98, Windows NT / 2000 / XP, Linux, Unix for PC. Active@ KillDisk conforms to US Department of Defense clearing and sanitizing standard DoD 5220.22-M. You can be sure that once you clean up with Active@ KillDisk, sensitive information is purged out forever. We highly recommend you to run this FREE utility for the hard and floppy drives you want to dispose of, recycle, re-use, sell or donate to somebody.Attention: This will leave your computer with no operating system