Those are both from BikesDirect.com originally - yes? There's too many variables at play to give an educated answer. Starting with: Who built them up? Did the person hire a bike-shop mechanic to do the job? Or were they just screwed together with some WD-40?
Personally I'd counsel that - unless you are a bike-mechanic who has built bikes up from the bare frame - that you buy a bike from a bike-shop. This may appear to cost more, but it may well save you a fortune. This way you get specific guarantees and warranty. For instance most shops will fine-tune anything that comes loose during, say, 6 months. Some manufacturers' give a lifetime warranty should the frame ever break. You get a full tune-up within the first 6 months. So forth - read the fine-print. This can save you a bundle of money down the road <koff>.
If you buy used, you get no warranty - unless it's from a bike-shop also.