The Asus A7V600-X actually has some features that the A7N8X-X does not. Like RAID support, SATA support...
Of course you really should take this advice:
"We´d like to make customers aware that AMD will soon be discontinuing the Socket A platform. So if you´re designing a PC with future-proofing and cost-effective upgradeability in mind, we strongly recommend that you look at AMD´s Athlon 64 CPUs and our range of Socket 754 and Socket 939 mainboards."