Well I upgrade my Lenovo ThinkPad W520 from Windows 8 to Windows 10 Release Preview. The upgrade worked flawlessly (thank you Microsoft!). So I’m checking out my new digs on the new OS and opened up Windows Explorer. Very nice! The new ribbon feature add great additional functionality to the tool. But I saw that there were a few new folders added ($WINDOWS.~BT and Windows.old). Naturally I assumed that it was the folders used in upgrade process. So I decided