Boot to the DVD.
Please be advised that you are trying to install a 64 bit version of Win 7 on top of a 32 bit install. The 'upgrade' is possible, but requires a clean install. You may NOT run 64 bit Win 7 from inside a 32 bit OS. You must boot to the DVD and do a clean install. Your applications and data will be located in a folder called WINDOWS_OLD when it is all done.