no 667 is just as fast or faster.
While DDR2-800 looks nice on paper, it's simply not necessary to get the most performance out of your system, As long as you've got low-latency memory modules, DDR2-667 will perform just as well as DDR2-800. The explination behind this is simple: Core 2's FSB runs at 1,066MHz but is only 64 bits wide, delivering 8.53GBps of bandwith to the CPU. Core 2's memory subsystem is 128 bits wide but even at DDR2-667 can deliver 10.67GBps of bandwith, meaning that unless its FSB Frequency is faster than 1,333MHz, the CPU can't use any more memory bandwith. So its almost pointless to spend the pretty penny just to say you own DDR2-800 when you get no benifits.