Download the Ultimate Boot CD (
www.ultimatebootcd.com) from here:
http://pub.windowsbase.de/ubcd/ubcd502.isoBurn the iso file to a blank CD with ImgBurn (
www.imgburn.com) selecting 'Write image to disk'.
Then boot the laptop off it.
In the boot menu, HDD > Disk Wiping Tools
Select any of the wiping tools offered. I recommend DBAN (Duke's boot and nuke). Done.