first back up all your personal files and pictures to a DVD, thumb drive, etc...If the machine is unable to run,
take out the drive, install it as a second drive in a working computer, drag your files off the bad drive and make a backup.
Or have a computer shop do it for you...
Before you switch operating systems, you must backup the files and pictures, or you may loose everything...
Now you will need a XP or win 7 install disk, do you have your disk ready?