Easiest solution is to copy all critical data files (and music files) to either: Off disc media (cd, usb drive, external hd) and then delete the old windows installation and then copy the files back to the system OR move the data in the folders to a folder in the new Windows installation and then delete the old Windows installation. To delete the old Windows, just boot to the new install, open Windows Explorer, and delete the other (old) Windows folder. Don't worry, you cannot delete the folder of the version to which you have booted.