How can i load the O/S on D-Drive with a disk and then format C-Drive. then load The O/S back on my C-Drive which is a Samsung 840 Pro SSD . I did a clean install of c drive with win 7 pro and it was 120 GB On the drive i Deleted the old win. File and it was still 75 GB I have all my music and pictures saved on a back up i just wont the Operating System Only.