Gah! Donate Windows 7 laptop

My sister treated herself to a new laptop and her old one is up for grabs. It's on it's last legs, but a casual user might enjoy it.



I've copied everything off it and would like to get rid of all her stuff and just leave it like a clean install.



Is it possible? We don't have any disks.



Thanks

via ehMac.ca http://ift.tt/1bR9b9e