Why not get a HP DL585 and only populate it with 2 CPUs? It has more than enough drive bays for you and later, if you need it, you can add two more CPUs, even dual core ones. Alternatively, get a Sun Vz40 and again populate it with just 2 CPUs. Thirdly, get a 5U 2P Opteron from HPC: http://www.hpcsystems.com/as5224.html . It has 24 hot swap bays. You can take any rackmount and simply put it on a shelf (or the floor)with unrestricted sides, front and back and it will work fine.