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
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.