1) How much money are you willing to spend?
2) Are you willing to accept the fact that this system may not play games well?
Assuming you can afford to spend a crapload of money, I can recommend a system that will be overkill for this program.
Start by getting a Tyan Thunder K8W motherboard and 2 Opteron 250 processors. This particular setup has gives each processor it's own dedicated memory path. Load it up with as much registered memory as you can afford. Suprisingly, 2 Zalman 7000-AlCUs can cool this beast.
For a video card, I would seriously examine the Matrox line. The P650 is a great passive Dual-DVI card. The P750 and Parhelia give you triple head support, though you get active cooling in the process. The G200 & G450 MMS series can give you quad head support, though. The G200 appears to be passive and the G450 appears to be active, though it's not clear if that's across the board.
(Interesting note: If you decide to spring for the G200 MMS, you can probably save money on the motherboard by going with a Thunder K8S, which doesn't actually have an AGP port).
For monitors, I would examine 9x Media
, though Viewsonic has some respectable offerings as well
The power supply can be done by any decent 400W PSU. A decent 300W PSU can probably take care of the above listed system, but I wouldn't push it too far. A Samsung 160GB hard drive is probably more than plenty for your needs as well. Though if you really need size, it's my understanding that Hitachi is currently reigning as size king with their 400GB hard drive.