It's the fastest board around. But to be honest, you're probably not going to take full advantage of the bandwidth as you suggest. In the future, you will see the advantage of it as software matures. Developer's of games and such are sooooo far behind of hardware now, it's not even funny. Microsoft's Vista won't even be out until next Christmas, another delay in the pure 64-bit operating environment. A lot of games however, are multi-threaded to take on dual core, but don't know about SLi. If you do buy this now, this motherboard should last you for a long time.
Or you can buy a cheaper motherboard (half the orice of this Asus one) and upgrade in the next few years.