Something like this may work. http/www.vista-files.org/programs/egis-technology-inc/trust-delete.html, never tried this type of software before.
You can also setup a PXE boot environment and boot the computers to that, which will enable you to put an image on the computers remotely. http/www.google.com/search?hl=en&source=hp&q=setting+up+pxe&aq=f&aqi=g10&aql=&oq=
Since you can't format a system drive while Windows is running, you need to format the drive after booting to an external media, which means you either need to be there to boot the computers, or have them boot to PXE.