Windows Lost and Found files/directory

I was thinking about selling / trading in my old laptop but there may be a lot of personal information which I thought is deleted but its all stored in that lost and found area i think, does anyone know how to completly destroy the files?
I am currently trying a program called, File shredder
Using this ‘Shred Free Disk Space’
My O/S is Windows 7
Answer #1
Reformat computer. Webroot Window Washer has that setting for wiping HDs the way government does it so nothing can be obtained with recovery tools. But many have said Webroot has spyware embedded to it. So worth a try. After all you are here in forum
Answer #2
Moving to the Helpdesk section.
Answer #3
Ok well, I started using this tool called directory snooper, and it showed like over 400k files which I deleted through windows, I managed to wipe/purge them all and i tested a file recovery software and it doesnt display any files any more, apart from my most recent ones.
Answer #4
I’d use DBAN if i were you , It will wipe out everything