Memory Bandwidth vs. Latency Timings
While bandwidth is still very important to the Intel Pentium 4, it's not as important as it once was in the i845PE days of single channel memory controllers. Thanks to the i865PE/i875P's dual channel memory controller things are much brighter. On average, the system with the memory running at 400 MHz (5:4 memory divider enabled) with aggressive memory timings performed 2-3% faster than the system using high speed memory with loose timings.
so get yourself some BH5-chipset memory for christmas this year! (I head OCZ is producing them a-new)