Well it all depends on what chipset you want...
The MSI 694D Pro and the Abit VP6 are both VIA Apollo 133A powered motherboards, which means you do get drastically low memory performance.
The OR840 is powered by the i840 chipset, meaning you have to use RAMBUS Direct RDRAM, which, though substantially cheaper than before, is still hugely expensive.
Finally there are boards based on the ServerWorks LE III chipset. This is a high end chipset which has VERY high memory performance - this would probably be your best bet, but the initial cost of the board is expensive.
So there you are... your choice is probably between these three chipsets - make an informed decision - all will serve you well.
Good luck
