8 monitors =
2 dual head vid cards + two 3HTgo
You really NEED a multi core machine to run this kind of setup.
I suggest a Quad core with as much memory as you can afford.
This one is a bit pricey but it will handle 16 cores. Of course, you will need a 64 bit OS for that many cores...
http://www.supermicro.com/products/m...7300/X7QC3.cfm