If it has SATA, then by all means get it! I think only the expensive Deluxe versions of the A7N8X have SATA. Both Asus mobo's should have plenty of OC'ing features if you want to mess with that.
As for the chipsets, it's true that the A7N8X uses the NForce2 chipset and therefore has dual-channel RAM, but I find most of that goes to waste on the AMD platform. The CPU itself just doesn't have the bandwidth of the P4 and therefore only gets a small boost from dual-channel. Benchmarks show 3-10% on average, with 10% being very hard to hit and only in certain games.
IMO, if you want better game performance, you're better off getting an expensive graphics card! CPU power, RAM, and graphics cards are the only sure-fire way to improve gaming performance. Playing "chipset roulette" only gets you so far.