Ive just built a dual processor Tyan Thunder n3600B S2927A2NRF running two dual core AMD Opterons and a Gigabyte iRAM drive which the OS is running in and SATA RAid 0 for storage which mega quick

People so often believe that dual core systems are as fast as dual processor which is simply not the case as the dual core systems are restricted as they share the same memory bus.
Obviously memory is faster than a hard disk and by running the OS on the iRAM drive provides unbeatable performance and bandwidth.

look on you tube for iram to see how quick systems boot and run using it.

Its not a cheap rig, specially when you take into consideration the vapochill case its running in but a dual SMP dual core rig runs well