I've never bought one myself so I don't know what manufacturer to select. But look for something mid-priced with good reviews. Yes you can buy a computer and the enclosure or just the enclosure and use your son's. There should be instructions with the device. Look for one that shows some kind of nice box instead of a standard shipping box. Also don't get one that says "OEM" as that, although cheaper, won't have a manual and it might not have a cable. You should be able to figure it out. You only need to transfer your files and not windows its self.