I'm not much of a fan of refubs or PC world. While refurbs seem like a good idea, the change of failure of a component in a PC increases by about 6-7% per year, so anything that has been in use already greatly increases the chance of failure.
Actually, the complete opposite is true. For nearly any Electronic component like a CPU or motherboard, or video card, if it's going to fail, it will do so within a week or month of first use.
Also going by your math my Toshiba 440CDX that was manufacturered in 1995 has a 47 percent chance of inexplicably failing at any given moment; something which you would expect might be indicated by something other then it working perfectly fine. (alright, so the hard drive has a number of bad sectors, but hey, the hard drive is only supposed to last maybe 5 or 6 years).