Looks like this is all I'll need if it works properly: http://www.killdisk.com/downloadfree.htm
Can anyone vouch for KillDisk?
I most certainly would NOT vouch for any non-FOSS program to do this job.
DBAN supports everything from the simple drive zeroing, to the DOD standard overwrite, to the super-overkill Gutmann method of overwriting the drive 35 times.
Not to mention UBCD is just a useful tool to have in general since it includes so many useful programs.
I use DBAN to stay HIPAA compliant for my job.
KillDisk free only supports one-pass zero. While arguably this is enough, I believe at least a 1-pass random write should be done if not the DOD-short (3-pass) or DOD-long (7 passes, HIPAA-compliant).
EDIT: Oh, also, if any of these drives are SSDs, the only way to erase data is by removing the drive and physically destroying it (preferably with thermite with the fun recorded and uploaded to Youtube). SSDs cannot be successfully overwritten by standard means and physical destruction is the only way to guarantee data destruction.