For stability, get the 875 chipset and ECC memory. The 865 doesn't
support ECC. Also, most BIOSes implement Intel's PAT (Performance
Acceleration Technology) in the 865 chipset even though it isn't
officially supported by Intel for the 865. So they're essentially
overclocking the chipset. Not sure, but maybe this can be disabled
in the BIOS for 865 motherboards.
I think the better, though newer, Asus 875 motherboard is the P4C800-E
Deluxe. The P4C800 Deluxe is based on a board that was one of the
first 875 boards on the market and Asus took a few shortcuts, such as
using a 3COM GB ethernet chip and not taking advantage of the CSA bus
for the gigabit LAN.