So you'd like to undo RAID-0, perhaps because you're replacing the array with a single SSD, perhaps for other reasons.
As far as I can tell there's no "undo RAID-0 but keep my data" option. Most of the articles on the web boil down to "copy your data off the RAID-0 array then delete it."
I've periodically kept a few backups to an external 1TB USB drive. So much of the data on the RAID-0 array has already been backed up.
But how to determine which files have been modified since my last backup?
I love Windows Search. In Win7 (and earlier versions) the following query does the trick:
datemodified:>9/1/2012 NOT kind:music NOT kind:folder
All of my music is backed up to Amazon's Cloud Drive so I'm not worried about backing that up.