I just read this on wikipedia:
Unlike the previous Pentium 4 and Pentium D design, the Core 2 technology sees a greater benefit from memory running synchronously with the Front Side Bus (FSB). This means that for the Conroe CPUs with FSB of 1066 MT/s, the ideal memory speed is PC2-4200. In some configurations, using PC2-5300 can actually decrease performance.
However, there is no reference. Has anyone stumbled across discussion of this "fact"?
Thanks for the question and information, I intend to buy a new computer in a couple months when I have the money.