But I did have it after the upgrade. I upgraded Win8 to Win8.1 on my Surface, no custom installation, not formatting any partition and I did have a Windows.old folder in my root directory because I checked it to see the size (3.8GB) with the plan to remove it later via Disk cleanup. But when I did it wasn't there. Very strange. Could an automatic update have deleted it? I still have the same free SSD space on my C drive, not 3.8GB more than after the update (the update gave me about 5-6GB more space than I had in Win8.