We have 2 old computers, desk top that are no longer needed/wanted. Both were used for business, now as said no longer needed.

Want to pass them on, maybe local school whatever but need to ensure that no info personal or business is left on them

What's the best way to totally clean them.

Reformat the hard drive

Reformatting the hard drive doesn't securely wipe the data. You can't do it while the computer is running, either.

If you can put a hard drive in another computer as a second drive you can use the free and downloadable CCleaner to securely overwrite the data.

You can't do it to the disk that's running Windows while it's running. You could download Bart's boot and nuke for free, burn it to a CD, boot from that CD and nuke it.

I would prefer the first way for a beginner even if I had a different wiping program. Getting the computer to boot from a CD and running it that way might take a little expertise. If you want to try it post back. Otherwise nuke it while it's installed in a different computer.

BTW it takes many hours for a wiping program to securely overwrite the data so don't stay up late, LOL. Just let it run.

43 Free Data Destruction Software Programs (updated June 2015)

http://pcsupport.about.com/od/toolsofthetrade/tp/free-data-destruction-software.htm

Eraser ! Overwrite data 1 to 35 times (3 times is usually enough). Can also overwrite free space on the drive. Leave the OS , for the next owner. Uninstall programs that you don't to keep on the drive.

Eraser is free.

Actually one time is more than enough, unless the information is valuable enough to warrant data recovery by reading the hard disk platters with a tunneling electron microscope.

If that is the case, don't use eraser, but more permanent measures, don't recycle it.