You best run the utility from your hard drive manufacturer.
Those tools can erase all data (that other tools can't access, like remapped sectors) and they are much faster than the normal wiping programs.
See my post (post #13) at:
http://www.boot-land.net/forums/index.php?s=3a0b531c7884bfce2f8ed882286a8fcc&showtopic=8935&st=10
Read the PDF file to which I link in that post. It mentions times needed to wipe a disk for different modes.
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Download
Ultimate Boot CD v5.0:
http://www.ultimatebootcd.com/download.htmlUse
Parted Magic for handling all partitioning task:
http://partedmagic.com/