Well, OK, here's the deal.
The RAM you're refering to is Double Data Rate, that means 166MHz clock rate has a 333MHz data rate. The CPU you refered to is Quad Data Rate, 133MHz clock rate has 533MHz data rate. Dual Channel allows the RAM to have twice as much bandwith as single channel, to match the CPU.
Given that information, PC2100 (DDR266) Dual Channel would be fine for a 533 bus CPU. I don't know why they are using PC2700 (DDR333) unless it just happens to be cheaper at the moment.
Either way, DDR400 doesn't come into play until you have an 800 bus P4. The 800 bus is a perfect match for DDR400 Dual Channel. The added bandwidth of DDR400 would be unused by the slower 533 bus speed.
<font color=blue>Only a place as big as the internet could be home to a hero as big as Crashman!</font color=blue>
<font color=red>Only a place as big as the internet could be home to an ego as large as Crashman's!</font color=red>