For sale, 640gb external Seagate HDD Selling as I now have a dual internal HDD setup in my desktop PC. I have fully reformated the HDD. It shows 640gb capacity on the back, but when plugged in it is only 600gb. (I had a Freeagent go which was 200gb but only showed 180gb!! Must be a Freeagent thing!!) There are some light scratches on the base shown in picture 4. Picture 2 shows its capacity, I used this external HDD on Vista Pro and now on Windows 7 HP.