Disk Wipe Software

DBAN - Darik's Boot and Nuke  - http://www.dban.org/

Active@ Killdisk will do this and is free.

http://www.killdisk.com/

Do not that running such erasures will typically take awhile as multiple (and thorough) passes are made to write data to the drive in question in order to ensure that recovery is virtually impossible.

Both are good programs. My input is this....

DO NOT press enter without knowing which disk your pointing at :-)

I've seen more that once, a person slaving a HD and choose the wrong drive....DOH!!

I was going to suggest DBAN as well.  You can put it on CD, DVD, or 3.5 inch diskette.  Just use the autonuke selection and let it go.  It will take some time depending on your disk size.

Not a lot of people are aware of this neat little tool that comes with ccleaner from Piriform. You can use it to securly wipe the contents of empty space or a full drive. You can securely wipe the data 1, 3 or military wipe 7 or 30 times. Take the Hard disk out of the computer you want to wipe, Hook it up with a IDE/SATA to USB adapter kit to a different pc. Go into CCleaner, Its located under tools, drive wiper. Choose the ***correct drive,***  Select Entire Drive from the "Wipe" Free Space pulldown.
CCleaner is FREE and I use it on my entire network of 100+ pcs all the time.

http://www.piriform.com/ccleaner/download

you can erase all dat from the disk with the manufacturer's diag (write 0)
best download ubcd to make a bootable cd - it has them all : http://www.ultimatebootcd.com/      

>>  I need to completely wipe the data off of a hard drive  <<   also you should give more info :
what do you want : the data to be UNrecoverable, or just clear the drive?
for the first, DBAN is good
for the second - just delete the partition(s)

MICROSOFT DART TOOL

http://technet.microsoft.com/en-us/library/ee532075.aspx#_Toc241331388

you can wipe from it also.