For LGA 775, DDR1 or DDR2 support depends on the chipset; I know 925X is DDR2 only, but the 915 series has chipsets for both. PCIe's a non-issue right now--AGP cards are just fine. If you are insistent on the 3.2 Prescott, get the S478, but for around the same money you should be able to get an A64 3400+, which will mop the floor with that P4 and should overclock somewhat respectably too.