The docs won't necessarily be copied over because Windows just doesn't do that. That being said, the chances of any work product being in the Windows directory these days is basically zero. Under older versions there was a chance, but these days not so much.

If you want to consider deleting that folder you can rename the windows.old001 folder to something else (e.g. windows.skiadcock) for a few weeks to make sure that you aren't missing anything and then delete it.

As for checking free space on your HD, in the my computer view right-click on c: and choose properties. You'll get a pretty pie chart with free space.