Don't get me wrong, I'm not knocking the PC1600, if you have a 200MHz CPU this is what you want! However, if you are going with a 266MHz CPU, you'll need to get PC2100 since if you used PC1600 you would have a FSB of only 200MHz and would really be restricting your capabilities.
I have seen quite a few people underclocking their DDR memory by using 200MHz CPUs and PC2100 DIMMs. They do this as they are still waiting for the new CPU's and wanted to get RAM early. Personally, I would try to get the CPU first, and then hopefully by that time the prices of the DDR memory will have come down a tad. I guess were going to have to wait until the end of March to find out for sure.
Of course, I could be completely off base with that statement in that when the new 266MHz CPUs start shipping in quantity, we could see a run on DDR RAM creating shortages. Just a heads up, as I really have no way of predicting what will happen.
Steve Benoit
Stable Technologies
'The way IT should be!'