Quad 64-bit processor
A computer processes information in "words". Until recently those words were 32-bits long. Newer computers can process words twice as long 64-bits which makes them somewhat more capable. 64-bit processors are the new standard. Just a short time ago Dual processors were the new thing. It's now Quads (4).
Video card with 2 monitor outputs and a GPU with at least 1 GB on memory for OpenGL capability.
Photoshop, begining with CS4 can use some of the memory on the Graphics Processing Unit, a separate computer on the videoo card. That capability enables features heretofor unavailable.
An IPS monitor (not TN).
This is about the technology that makes the display, display. TN (Twisted Nematics) monitors are inexpensive but they have very limited viewing angles and cannot be calibrated as precisely as IPS (In-Plane Switching - TFT LCD - Wikipedia, the free encyclopedia)
2 monitors is better for image editing (image on 1 screen, tools and pallets on screen #2).
A minimum of 500 GB of internal storage space, preferably 2 internal 500 GB hard drives (1TB), and at least 1 external 500 GB hard drive.
Photographs are big as far as data files go, though video files are larger. An editing workflow that insures against the loss of precious irreplaceable photographs results in multiple copies of a photograph: original, edited, and output. Plus, again related to the way image editing software works, it speeds the editing process up if there is plenty of internal "scratch disk space".
Plenty of fans to keep everything cool and a big enough power supply to run it all.
Heat is the #1 killer of electronics. Insufficient power is the #2 killer of electronics.
47 USB ports and 14 Firewire ports.
You can never have to many auxiliary ports for plugging in any plthora of consumer electronic products.
