if its one of the higher end Quads like a q9650 with 8gb of ram, and a decent enough GPU like 750ti/r9 270x or above at 1680 x 1050, then you would be okay for a while. Specially if the CPU was overclocked, otherwise its gonna struggle a little with todays games. The likes of BF4/COD Ghosts etc require 6gb of ram, a solid quadcore and a good GPU to perform at med to high settings, so you can see where I'm going with this.
If your buying it, then don't, save up some more money for a newer system. If you have it already and are trying to stretch it out before purchasing, you'll just find more and more it's lagging behind.