If you're referring to our recovery ISO, it's not a free copy of Vista. It's a MS repair disk.
It has no installation files so you cannot use the "install" button.
It's provided for the "repair your computer" link bottom left, just to enable you to reach your OEM recovery facility if your OEM PC has become unbootable.
If the OS is corrupt in some way, you must use the OEM provided media to fix it.