What software are you using? Is this to be a dedicated machine for one process or an all-in one?
For grins, my budget machine is a Gigabyte GA-MA770TUD3, AMD Athlon II 3.1 x2, 12 GB DDR3 1333, WD Caviar 250 GB SATA, nVidia 7600GS 512MB Dual-DVI pci-e video card, CoolerMaster extreme 460w power...