Gigabit Ethernet Server
This one is a problem. Gigabit ethernet has approximately the same bandwidth as the PCI bus, so if you expect to use most of that gigabit bandwidth you will also be using most of your PCI bandwidth. That's a bottleneck you'd like to avoid. The solution is to use 64bit 66MHz PCI, which most gigabit ethernet cards support. However, this severely limits your choices for the rest of the system. The only chipset which currently supports fast wide PCI is the i840. (The Micron Samurai chipset will support it too, but isn't quite out yet.) As noted earlier, the i840 is designed to work with RAMBUS memory, which sucks, but if it's your only choice then the question becomes how to make it suck the least. You can either use actual RDRAM, which is hugely expensive, or you can use regular SDRAM via the "memory translator hub" which is slow. Plus Intel recently admitted that the MTH causes crashes! That's a showstopper, so we must go with RDRAM. This narrows down the choice of motherboards. Intel's reference i840 board, the OR840, uses RDRAM but does not do fast wide PCI. SuperMicro and Tyan both have i840 boards with fast wide PCI, but they all use SDRAM/MTH only, no RDRAM. Then there's the Iwill DCA200 Four RDRAM slots, two fast wide PCI slots (plus four regular PCI). Just what the doctor ordered. Couple of minor drawbacks: it's WTX form instead of ATX (WTX cases are expensive), and it's Slot-2 instead of Slot-1 (there's an adaptor, or you could use Xeons).

Woo hoo! Note that to take advantage of the i840's dual RDRAM channels you must install RDRAM in identical pairs; a single 256MB module will not work.