If you're trying to install Windows XP over your existing Vista installation on a GT5628, Gateway recommends that you follow the instructions here. Unfortunately for Gateway, the instructions on that link are not instructions on how to do anything, let alone Windows XP installation instructions. I think they meant to send me this link which would actually be useful if I just wanted to know how to install Windows XP. Unfortunately for myself and my client, I am unable to install XP over Vista on a GT5628 because the install process is unable to detect the hard drive (I've tried both SATA and PATA) that is attached to the machine. If anyone has been successful in installing XP on a Gateway GT5628, please leave a comment and let me know what you did. I spent hours and hours trying to get it done.