Reburished computers are computers that have been returned for a number of reasons:
1. They did not work, but the shop/company would have fixed the problem before they sold them as refub computers.
2. A computer the customer did not want or could not afford, so they sent them back.
3. An ex-display computer.
Also refurb computers dont always have the same warranty as new computers, so you need to check before you buy.
The only real risks are the warranty and that they sometimes dont come with all the manuals cables (but then they will tell you).