You can't do a clean install "and" retain your already installed programs. You will have to re-install your programs after the windows clean install. You can backup your files such as documents, pictures, etc to external media before hand though. And then just copy them back to their respective folders after the re-install. Clean refers to wiping the drive clean before installing windows. You could copy the program folders to external media but each program makes entires into the windows registry when installed. Those entries will be lost when windows is re-installed and the programs won't work if you try to copy them back in to the program files folder. They will have to be installed again to work correctly.