A friend of mine lost the password to a netbook he hasn’t used in years, to find it for him I used a program called Ophcrack.
There are ISO files for bootable cds on their website, but as his netbook doesn’t have a cdrom drive this wasn’t much use.
I tried several programs like unetbootin but none of these would boot correctly and gave messages such as ‘missing operating system files’
In the end I found that pendrivelinux.com had support for Ophcrack in their Universal USB Installer.
I downloaded the installer, ran it and selected Ophcrack for vista/windows 7. The installer then downloaded the correct iso and made a bootable copy on an inserted USB key.
Download the Universal USB Installer and give it a try.