Use Eraser, it's free and fast.
I you sell your HD to a normal PC user, use a simple one-pass erasing procedure.
3, 7 and 35 pass rewriting are needed only for commercial, enterprise and critical activities where a concurrent could (spending a lot of money and time) try to recover information about patents, customers, military info, etc.
But for personal use and normal users a single pass is all you need: there is no software or standard controller that can recover rewritten data, you need extremely expensive electonics equipment to do that.
I you sell your HD to a normal PC user, use a simple one-pass erasing procedure.
3, 7 and 35 pass rewriting are needed only for commercial, enterprise and critical activities where a concurrent could (spending a lot of money and time) try to recover information about patents, customers, military info, etc.
But for personal use and normal users a single pass is all you need: there is no software or standard controller that can recover rewritten data, you need extremely expensive electonics equipment to do that.