Freeware Hard Drive Wipe

I am trying to phase out my older lab PCs in favor of VMs, so I went looking for a utility to completly wipe the hard drives in them. I thought I would be able to easily find a bootable ISO that would do this, since most of the computers have no floppy drives and the ones that do usually don't work anymore. Apparently there are some paid/shareware utilities out there for this, but I wanted something freeware.

So I found a bootable ISO that does nothing but boot (from www.bootdisk.com) and a freeware application to wipe the drive (from Dr. Gordon F. Hughes at UCSD). Put the two together with a little ISO manipulation with WinISO and there you go, one freeware drive wiping utility on a bootable CD.