All our media is XDCam movs,

no backups of cards, so we'll backup the move (and hope they're all OK!)

along with each mov there's a corresponding XML file.
i'm assuming we don't need them anymore... correct?
i want to trash them all, but can move them elsewhere if needed.

I honestly can't remember if FCP legacy needed the XMLs intact. I would try moving one and see if it breaks the corresponding media file. Some of those structure things are set in stone in older systems.