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.
Download Ultimate Boot CD v5.0
Use Parted Magic
for handling all partitioning task: http://partedmagic.com/