This will show you how to do custom installation of Windows 7 to have a new clean install of Windows 7, but with everything from your current Windows installation backed up into the
Windows.old folder during this custom installation. After the custom installation, you can copy any files you wanted back from within the
C:\Windows.old folder back into your new installation of Windows 7 and
delete the Windows.old folder when finished.
Like with a clean install, you will need to install all of your
drivers and programs again after doing a custom install of Windows 7.