So what is the Windows Old file do since it has all that was on the XP?
Great question. I've wondered about that, too, and whether it's OK to get rid of it.
Gil.
I would keep it for at least 2 weeks, it contains files that you may need that were missed in the original transfer, once you are satisfied that all is good then you can safely ditch it, here are a few links that explains the why of Windows.old:
On a good desktop, you can't tell the difference between the performance with and without Aero. But on a tablet, it would definitely show up. I love my Surface!