I have a brand new 1TB HDD which I plan on replacing my old 500GB HDD with completely and I plan on using the old HDD as an "extra" hard drive just to store extra stuff on or whatever but it has windows 7 and a bunch of stuff on it. My question is how do I COMPLETELY delete everything on the hard drive so that it is basically how it was from the factory when empty? I have heard of programs like KillDisk and a couple others but do these wipe HDD's completely clean or do they render them useless after wiping the data on them? Thanks so much in advance!!