Most obvious conclusion ever

"So the best way to move 60 million files from one Windows server to another turns out to be: use Linux."

D'oh? On a serious note, you should also give rsync a go. And try also _storing_ the data on an OS that is not windows, you might find that you are then able to do things you need to do, like say copy 60m files, without resorting to booting virtual machines of another OS just to use that OS's utilities to manage your main OS. Just saying. Please don't flame me.