A 500-600 mhz overclock? With Venice 3200+, I heard that one review site got a 700mhz overclock WITHOUT CHANGING THE VCORE. Pretty cool. I'm fairly confident you'd be able to pull the 500mhz clock off with the A8N-E, I did it with a 3.0 PresHOTT to 3.6 on an ASUS P4P800-e Deluxe.
But you got to remember, not all CPUs overclock well, it's usually your luck.
-TPG