Since they moved to QPI from FSB, I haven't the faintest on how it relates exactly either, but it doesn't really matter, inless you plan on some overclocking.
1066 is standard, 1333 seems the butterzone; any faster and gains become minimal, 1600 is the upper standard speed. There are modules with even greater bandwith, but usually comes at the price of latency and a price-premium.
For example, I have a Kingston kit right now of 800MHz DDR2, which has lower latency (imho more important than bandwith for games) than my previous Kingston 1066 kit.
I'd just go with 1600, maybe 1333 if it offers better latency. If you get an i7 920 with the triple-channel, bandwith shouldn't be a concern anyway.
Smartass comment: DDR3 isn't faster, it just has more bandwith, which can translate to better performance, given the timings/latency isn't through the roof (like it was at release, came a long way since then).
