At the outset you must know that a REFURBISH is different from USED COMPUTER. Refurbish is usually examined by experts and necessary repairs have been done by the manufacturers whereas, used computers haven’t gone under any kind of repairs.
You must verify the used computer in the store before making a purchase. If the computer boots up, just look for other specifications. You should know how to verify the system properties. Just click on Start button present on the down left corner of the screen then on Control Panel and then on System and then System properties, basic system properties will be seen here such as processor type and speed, amount of RAM and the operating system in use.
Always try to get any warranties if they are offering. Mostly they give 15 days warranty and refuse to return after elapsing of this period. In case you need a repair after warranty period, you have to deal directly with the manufacturer which is time consuming and costly or consult your local repair store for repairing as an alternative. This is why many used computer users develop basic repairing skills as well.
You should also ask for the computer operating system set up/restore disk(s) while purchasing a used computer so in case of any operating problem you can set up the operating system on your own which requires a reformat of your hard disk first which erased any settings and your data present on it.
It is therefore wise to copy you valuable data on back up disks such as your USB or CDs. Installation of Operating System is not hard and you can do it on your own by following the simple steps guided by the wizard and it takes less than an hour to complete the installation. Even then if you find any complexity or facing shortage of time, you can ask your repair shop for installation of operating system with very minimal charges.