Onto why you shouldn’t be using AMD at least right now in a $1000 server, it’s because of the boards. Obviously you don’t want a Via board, and while the NF2 is a fine chipset for the desktop, not so for a server. The 760MPX chipset works great, but the boards are expensive and you don’t have the performance given by the high bandwith of a Serverworks chipset, nor the RAS features (Reliability, Availability and Servicability) on higher end machines. While you could go with an Opteron, it is a more expensive option due to the expensive motherboard and $300 CPU, so that’s obviously not an option.
As an aisde, the configuration I drew up is available from IBM, Dell and other Teir-1 OEMs for about the same price in their prebuilt servers.